mq: defer command wrapping to extsetup (API)

mq wraps all commands that are not in commands.norepo, which is now performed in
this second phase of the extensions setup process.  This goes against the
current best practices on the wiki [1] as far as where command wrapping is
performed, but follows it regarding where global options are injected.

mq needs to be the first layer called when command dispatching in order to
consistently retarget to the patch repo, regardless of the load order of the
extensions.  This means being the last to wrap the command table.  Previously,
'hg <extdiff> --mq' would diff the main repo unless mq was enabled after
extdiff.

[1] http://mercurial.selenic.com/wiki/WritingExtensions

hgext/mq.py

@@ -3537,13 +3537,12 b' def revsetmq(repo, subset, x):'
     applied = set([repo[r.node].rev() for r in repo.mq.applied])
     return [r for r in subset if r in applied]
 
-def extsetup(ui):
-    revset.symbols['mq'] = revsetmq
-
 # tell hggettext to extract docstrings from these functions:
 i18nfunctions = [revsetmq]
 
-def uisetup(ui):
+def extsetup(ui):
+    # Ensure mq wrappers are called first, regardless of extension load order by
+    # NOT wrapping in uisetup() and instead deferring to init stage two here.
     mqopt = [('', 'mq', None, _("operate on patch repository"))]
 
     extensions.wrapcommand(commands.table, 'import', mqimport)
@@ -3568,6 +3567,7 b' def uisetup(ui):'
         if extmodule.__file__ != __file__:
             dotable(getattr(extmodule, 'cmdtable', {}))
 
+    revset.symbols['mq'] = revsetmq
 
 colortable = {'qguard.negative': 'red',
               'qguard.positive': 'yellow',