### Please describe the problem.
As a result of the steps below git-annex end up in a state with multiple remotes (pointing to a USB). The crux is that each has a different name, but same UUID and same path. 

All, except one of the remotes is marked as dead. During sync git-annex tries to sync to all of them, and quite surprisingly appears to be successfull. 

The core problem I guess is that git-annex mistakes one remote for another.

I was just experimenting with git-annex, but I think this could happen for real. You put stuff on a usb, you loose the usb, you mark the usb remote as dead, time passes, you put stuff on a different usb and type the same remote name. Bang, it gets the same UUID.

Not knowing much about git-annex it seems that it generates the UUID before checking for name clash and renaming?

### What steps will reproduce the problem?
Init ~/annex with CLI. (I had version 7, but probably bug on 5 too). Then add an example file, in my case "The Rust Programming Language.pdf". Finally mount usb drive at /mnt/usb.

    - 1) Start git-annex-webapp.
    - 2) Create an unencrypted usb remote using the webapp. In my case its name was "smallusb".
    - 3) Sync files to the drive. Verify all is ok.
    - 4) Imitate drive loss. Delete annex folder on usb drive: rm -rf /mnt/usb/annex
    - 5) Imitate drive loss. Change to ~/annex and mark smallusb (or smallusb1, smallusb2) as dead.
    - 6) Stop git-annex-webapp.

Repeat the steps 1-6 at least 2 times in a loop :)
git-annex appends a number to smallusb, hence the "(or smallusb1, smallusb2)".

### What version of git-annex are you using? On what operating system?
Arch Linux, version 7.20190504-gf98e97669 downloaded as a binary from git-annex website.

### Please provide any additional information below.

[[!format sh """
# If you can, paste a complete transcript of the problem occurring here.
# If the problem is with the git-annex assistant, paste in .git/annex/daemon.log

-- .git/annex/daemon.log
[2019-06-14 06:02:25.999232228] main: starting assistant version 7.20190504-gf98e97669
[2019-06-14 06:02:26.023575476] Cronner: You should enable consistency checking to protect your data. 
[2019-06-14 06:02:26.058871795] read: git ["config","--null","--list"]
[2019-06-14 06:02:26.064856922] process done ExitSuccess
[2019-06-14 06:02:26.065157988] Tor hidden service not enabled
(scanning...) [2019-06-14 06:02:26.136886408] Watcher: Performing startup scan
(started...) 
gpg: assuming signed data in '/tmp/git-annex.tmpxo2fXm/info'
gpg: Signature made Wed 08 May 2019 01:26:23 AM MSK
gpg:                using DSA key 40055C6AFD2D526B2961E78F5EE1DBA789C809CB
gpg: /tmp/git-annex-gpg.tmp28lKKy/trustdb.gpg: trustdb created
gpg: Good signature from "git-annex distribution signing key (for Joey Hess) <id@joeyh.name>" [unknown]
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: 4005 5C6A FD2D 526B 2961  E78F 5EE1 DBA7 89C8 09CB
gcrypt: Repository not found: /mnt/usb/annex7
(recording state in git...)
warning: no common commits
From /mnt/usb/annex7
 * [new branch]      git-annex  -> usb/git-annex
(merging usb/git-annex into git-annex...)
(recording state in git...)
[2019-06-14 06:02:45.460756129] main: Syncing with usb 
To /mnt/usb/annex7
 * [new branch]      git-annex -> synced/git-annex
 * [new branch]      master -> synced/master
[2019-06-14 06:02:45.731237811] read: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","show-ref","git-annex"]
[2019-06-14 06:02:45.736487217] process done ExitSuccess
[2019-06-14 06:02:45.736545194] read: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","show-ref","--hash","refs/heads/git-annex"]
[2019-06-14 06:02:45.741412826] process done ExitSuccess
[2019-06-14 06:02:45.741780286] read: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","log","refs/heads/git-annex..c19630d0a5366076f7da95a2a5fa2e3cfc51445e","--pretty=%H","-n1"]
[2019-06-14 06:02:45.74683984] process done ExitSuccess
[2019-06-14 06:02:45.746899694] read: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","log","refs/heads/git-annex..874014cc02ad2383e612a5a200691adfb279fab6","--pretty=%H","-n1"]
[2019-06-14 06:02:45.751857523] process done ExitSuccess
[2019-06-14 06:02:45.752059154] chat: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","cat-file","--batch"]
[2019-06-14 06:02:45.755772389] chat: git ["--git-dir=.git","--work-tree=.","--literal-pathspecs","cat-file","--batch-check=%(objectname) %(objecttype) %(objectsize)"]
[2019-06-14 06:02:45.760705559] read: git ["config","--null","--list"]
[2019-06-14 06:02:45.766315456] process done ExitSuccess
[2019-06-14 06:02:45.766455838] read: git ["config","--null","--list"]
[2019-06-14 06:02:45.771340045] process done ExitSuccess
[2019-06-14 06:02:45.77170679] read: git ["config","--null","--list"]
[2019-06-14 06:02:45.776625026] process done ExitSuccess
[2019-06-14 06:02:45.776753592] read: git ["config","--null","--list"]
[2019-06-14 06:02:45.782541882] process done ExitSuccess

[2019-06-14 06:02:45.784051825] read: rsync ["--progress","--inplace","--perms",".git/annex/objects/XV/v2/SHA256E-s11122109--bbf1b9a6d9bc3be5515e3114aea5a7cf7a93ea406bbe53cf37eef81ba578b73f.pdf/SHA256E-s11122109--bbf1b9a6d9bc3be5515e3114aea5a7cf7a93ea406bbe53cf37eef81ba578b73f.pdf","../../../mnt/usb/annex7/annex/tmp/SHA256E-s11122109--bbf1b9a6d9bc3be5515e3114aea5a7cf7a93ea406bbe53cf37eef81ba578b73f.pdf"]
SHA256E-s11122109--bbf1b9a6d9bc3be5515e3114aea5a7cf7a93ea406bbe53cf37eef81ba578b73f.pdf
     11,122,109 100%  480.71MB/s    0:00:00 (xfr#1, to-chk=0/1)
[2019-06-14 06:02:46.647226687] process done ExitSuccess
(checksum...) [2019-06-14 06:02:46.732000864] chat: git ["--git-dir=../../../mnt/usb/annex7","--literal-pathspecs","--literal-pathspecs","cat-file","--batch"]
[2019-06-14 06:02:46.732316108] chat: git ["--git-dir=../../../mnt/usb/annex7","--literal-pathspecs","--literal-pathspecs","cat-file","--batch-check=%(objectname) %(objecttype) %(objectsize)"]
[2019-06-14 06:02:46.737658146] process done ExitSuccess
[2019-06-14 06:02:46.737894862] process done ExitSuccess
[2019-06-14 06:02:46.738498152] Transferrer: Uploaded The Rust ..guage.pdf
[2019-06-14 06:02:46.739276009] Pusher: Syncing with usb, smallusb2, smallusb1, smallusb 
(recording state in git...)
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at bb6dbcca16e11c47a129063b29fc26e1af0b6529 but expected c19630d0a5366076f7da95a2a5fa2e3cfc51445e        
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at bb6dbcca16e11c47a129063b29fc26e1af0b6529 but expected c19630d0a5366076f7da95a2a5fa2e3cfc51445e        
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at bb6dbcca16e11c47a129063b29fc26e1af0b6529 but expected c19630d0a5366076f7da95a2a5fa2e3cfc51445e        
To /mnt/usb/annex7
   c19630d..bb6dbcc  git-annex -> synced/git-annex
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
From /mnt/usb/annex7
   874014c..bb6dbcc  synced/git-annex -> smallusb2/synced/git-annex
From /mnt/usb/annex7
   874014c..bb6dbcc  git-annex        -> smallusb1/git-annex
   874014c..bb6dbcc  synced/git-annex -> smallusb1/synced/git-annex
From /mnt/usb/annex7
   874014c..bb6dbcc  git-annex        -> smallusb/git-annex
   874014c..bb6dbcc  synced/git-annex -> smallusb/synced/git-annex
Everything up-to-date
Everything up-to-date
Everything up-to-date
[2019-06-14 06:03:26.105979618] Pusher: Syncing with smallusb3, smallusb2, smallusb1, smallusb 
(recording state in git...)
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at 63d983955552f44ad51550dd017da9d3e089bb37 but expected bb6dbcca16e11c47a129063b29fc26e1af0b6529        
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at 63d983955552f44ad51550dd017da9d3e089bb37 but expected bb6dbcca16e11c47a129063b29fc26e1af0b6529        
remote: error: cannot lock ref 'refs/heads/synced/git-annex': is at 63d983955552f44ad51550dd017da9d3e089bb37 but expected bb6dbcca16e11c47a129063b29fc26e1af0b6529        
To /mnt/usb/annex7
   bb6dbcc..63d9839  git-annex -> synced/git-annex
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
To /mnt/usb/annex7
 ! [remote rejected] git-annex -> synced/git-annex (failed to update ref)
error: failed to push some refs to '/mnt/usb/annex7'
From /mnt/usb/annex7
   c19630d..63d9839  git-annex        -> smallusb3/git-annex
   bb6dbcc..63d9839  synced/git-annex -> smallusb3/synced/git-annex
From /mnt/usb/annex7
   bb6dbcc..63d9839  git-annex        -> smallusb2/git-annex
   bb6dbcc..63d9839  synced/git-annex -> smallusb2/synced/git-annex
From /mnt/usb/annex7
   bb6dbcc..63d9839  git-annex        -> smallusb1/git-annex
   bb6dbcc..63d9839  synced/git-annex -> smallusb1/synced/git-annex
Everything up-to-date
Everything up-to-date
Everything up-to-date
[2019-06-14 06:04:26.120035368] Pusher: Syncing with smallusb3, smallusb2, smallusb1, smallusb 
Everything up-to-date
Everything up-to-date
Everything up-to-date
Everything up-to-date


-- .git/config

[core]
	repositoryformatversion = 0
	filemode = true
	bare = false
	logallrefupdates = true
[annex]
	uuid = 2517eda3-c212-486e-a3a8-ffc085b842ba
	version = 7
	diskreserve = 1 megabyte
	autoupgrade = ask
	debug = true
[filter "annex"]
	smudge = git-annex smudge -- %f
	clean = git-annex smudge --clean -- %f
[remote "smallusb"]
	url = /mnt/usb/annex7
	annex-uuid = c52d9a9f-9362-4698-bb1b-fee40779de4c
	fetch = +refs/heads/*:refs/remotes/smallusb/*
[remote "smallusb1"]
	url = /mnt/usb/annex7
	annex-uuid = c52d9a9f-9362-4698-bb1b-fee40779de4c
	fetch = +refs/heads/*:refs/remotes/smallusb1/*
[remote "smallusb2"]
	url = /mnt/usb/annex7
	annex-uuid = c52d9a9f-9362-4698-bb1b-fee40779de4c
	fetch = +refs/heads/*:refs/remotes/smallusb2/*
[remote "smallusb3"]
	url = /mnt/usb/annex7
	annex-uuid = c52d9a9f-9362-4698-bb1b-fee40779de4c
	fetch = +refs/heads/*:refs/remotes/smallusb3/*

# End of transcript or log.
"""]]

### Have you had any luck using git-annex before? (Sometimes we get tired of reading bug reports all day and a lil' positive end note does wonders)
I think this is genius software and just love the docs, the effort put into it shines through! :)

> [[done]]; not a bug --[[Joey]]
