This is specifically to get the latest version of http://drupal.org/project/fbconnect to work as its version pattern doesn't use regex groups, but I think it's a good thing to have in general.
The change is fairly simple - change line 738 in libraries.module (libraries_get_version) from
return $version[1];
to
return isset($version[1]) ? $version[1] : true;
Comments
Comment #1
sun"true" is not a valid version identifier in any way.
Comment #2
tstoecklerMarking this won't fix.
The issue for fbconnect Libraries API integration is #1318946: Notice: Undefined offset: 1 in libraries_get_version().
Per #1, the proposal in itself doesn't really make sense.
Also you can always specify your own version callback, if you want to do something fancy, i.e. something you can't do with regular expressions.
If there is something we can fix here, or if I misunderstood this issue, please re-open!