Help for SET KEEPTOPIC:

SET KEEPTOPIC enables restoration of the old
topic after the channel has become empty. In
some cases, it may revert topic changes
after netsplits or services outages, so it
is not recommended to turn this on if your
channel tends to never empty.

Syntax: SET <#channel> KEEPTOPIC ON|OFF

Example:
    /msg &nick& SET #foo KEEPTOPIC ON
