py3: use default dict iterator instead of iterkeys

These are the easy cases. Some cases in manifest.py will require more
careful inspection.

Differential Revision: https://phab.mercurial-scm.org/D2315

contrib/synthrepo.py

@@ -381,7 +381,7 b' def synthesize(ui, repo, descpath, **opt'
         ui.progress(_synthesizing, None)
         message = 'synthesized wide repo with %d files' % (len(files),)
         mc = context.memctx(repo, [pctx.node(), nullid], message,
-                            files.iterkeys(), filectxfn, ui.username(),
+                            files, filectxfn, ui.username(),
                             '%d %d' % util.makedate())
         initnode = mc.commit()
         if ui.debugflag:

hgext/convert/subversion.py

@@ -384,7 +384,7 b' class svn_source(converter_source):'
 
     def setrevmap(self, revmap):
         lastrevs = {}
-        for revid in revmap.iterkeys():
+        for revid in revmap:
             uuid, module, revnum = revsplit(revid)
             lastrevnum = lastrevs.setdefault(module, revnum)
             if revnum > lastrevnum:

hgext/rebase.py

@@ -589,7 +589,7 b' class rebaseruntime(object):'
                         date=self.date)
             if newnode is not None:
                 newrev = repo[newnode].rev()
-                for oldrev in self.state.iterkeys():
+                for oldrev in self.state:
                     self.state[oldrev] = newrev
 
         if 'qtip' in repo.tags():