pull: pass rev to check out as integer to postincoming()

I don't know if there's ever been a need for it to be a string (it's
been like that since 02f40b2ece3f (commands: use rev from remote repo
when updating as part of a pull, 2009-10-21)). I'm soon going to
require it to be an integer, so let's fix this first.

Differential Revision: https://phab.mercurial-scm.org/D3086

mercurial/commands.py

@@ -4034,7 +4034,7 b' def pull(ui, repo, source="default", **o'
             brev = None
 
             if checkout:
-                checkout = "%d" % repo.changelog.rev(checkout)
+                checkout = repo.changelog.rev(checkout)
 
                 # order below depends on implementation of
                 # hg.addbranchrevs(). opts['bookmark'] is ignored,