bundlerepo: use early return

I like avoiding patterns that lead to the pyramid of doom.

Differential Revision: https://phab.mercurial-scm.org/D1382

mercurial/bundlerepo.py

@@ -319,7 +319,9 class bundlerepository(localrepo.localre
                                [ctx.node() for ctx in self[self.firstnewrev:]])
 
     def _handlebundle2part(self, bundle, part):
-        if part.type == 'changegroup':
+        if part.type != 'changegroup':
+            return
+
             cgstream = part
             version = part.params.get('version', '01')
             legalcgvers = changegroup.supportedincomingversions(self)
@@ -327,11 +329,9 class bundlerepository(localrepo.localre
                 msg = _('Unsupported changegroup version: %s')
                 raise error.Abort(msg % version)
             if bundle.compressed():
-                cgstream = self._writetempbundle(part.read,
-                                                 ".cg%sun" % version)
+            cgstream = self._writetempbundle(part.read, '.cg%sun' % version)
 
-            self._cgunpacker = changegroup.getunbundler(version, cgstream,
-                                                         'UN')
+        self._cgunpacker = changegroup.getunbundler(version, cgstream, 'UN')
 
     def _writetempbundle(self, readfn, suffix, header=''):
         """Write a temporary file to disk