'export' is the official export format and used by patchbomb, but it would only
show date as a timestamp that most humans might find it hard to relate to. It
would be very convenient when reviewing a patch to be able to see what
timestamp the patch will end up with.
Mercurial has always used util.parsedate for parsing these headers. It can
handle 'all' date formats, so we could just as well use a readable one.
'export' will now use the format used by 'log' - which is the format described
as 'Unix date format' in the templating help. We assume that all parsers of '#
HG changeset patch'es can handle that.
See the Hg Book on why we actually want to detect this case:
http://hgbook.red-bean.com/read/mercurial-in-daily-use.html#id364290
Before:
$ hg up deadbeef
warning: detected divergent renames of X to:
...
After:
$ hg up deadbeef
note: possible conflict - X was renamed multiple times to:
...
No functionality change.
