### Please describe the problem.
The subdirectory sync mechanism for import/export of a directory remote does not work.

### What steps will reproduce the problem?
Setup a directory-type remote with exporttree and importtree set to yes.
After the third time of syncing, the content of subdir gets synced into the top-level directory.

(I tried repository versions 5 and 7)

### What version of git-annex are you using? On what operating system?
OS: Fedora 29 x86_64
[[!format sh """
git-annex version: 7.20190503-gfd57780d0
build flags: Assistant Webapp Pairing S3 WebDAV Inotify DBus DesktopNotify TorrentParser MagicMime Feeds Testsuite
dependency versions: aws-0.20 bloomfilter-2.0.1.0 cryptonite-0.25 DAV-1.3.3 feed-1.0.0.0 ghc-8.4.4 http-client-0.5.13.1 persistent-sqlite-2.8.2 torrent-10000.1.1 uuid-1.3.13 yesod-1.6.0
key/value backends: SHA256E SHA256 SHA512E SHA512 SHA224E SHA224 SHA384E SHA384 SHA3_256E SHA3_256 SHA3_512E SHA3_512 SHA3_224E SHA3_224 SHA3_384E SHA3_384 SKEIN256E SKEIN256 SKEIN512E SKEIN512 BLAKE2B256E BLAKE2B256 BLAKE2B512E BLAKE2B512 BLAKE2B160E BLAKE2B160 BLAKE2B224E BLAKE2B224 BLAKE2B384E BLAKE2B384 BLAKE2S256E BLAKE2S256 BLAKE2S160E BLAKE2S160 BLAKE2S224E BLAKE2S224 BLAKE2SP256E BLAKE2SP256 BLAKE2SP224E BLAKE2SP224 SHA1E SHA1 MD5E MD5 WORM URL
remote types: git gcrypt p2p S3 bup directory rsync web bittorrent webdav adb tahoe glacier ddar hook external
operating system: linux x86_64
supported repository versions: 5 7
upgrade supported from repository versions: 0 1 2 3 4 5 6
local repository version: 7
"""]]

### Please provide any additional information below.

[[!format sh """
mkdir importexport
echo > importexport/should_be_in_subdir.txt
mkdir annex-test
cd annex-test
git init
git annex init --version=7
echo > in_top.txt
git add in_top.txt
git commit -m "top"
git-annex initremote imexremote type=directory directory=../importexport encryption=none exporttree=yes importtree=yes
git config remote.imexremote.annex-tracking-branch master:imexremote
git annex sync --content imexremote
echo Files after first sync:
ls
git annex sync --content imexremote
echo Files after second sync:
ls
git annex sync --content imexremote
echo After third sync, the files from the subdir show up in the top-level dir
ls
"""]]

### 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)
git-annex does a great job in managing my distributed backups. Thanks!

> [[fixed|done]] --[[Joey]]
