py3: fix revnums in bookmark discovery to be consumable more than once

mercurial/exchange.py

@@ -658,7 +658,7 b' def _pushdiscoverybookmarks(pushop):'
     ui.debug("checking for updated bookmarks\n")
     ancestors = ()
     if pushop.revs:
-        revnums = map(repo.changelog.rev, pushop.revs)
+        revnums = pycompat.maplist(repo.changelog.rev, pushop.revs)
         ancestors = repo.changelog.ancestors(revnums, inclusive=True)
 
     remotebookmark = listkeys(remote, 'bookmarks')