bundlerepo: properly extract compressed changegroup from bundle2

Before this bundle repository were unable to work with compressed
bundle2. We use the same approach as with bundle1, we extract the
changegroup in uncompressed form into a temporary file.

mercurial/bundlerepo.py

@@ -277,22 +277,26 b' class bundlerepository(localrepo.localre'
         self.bundlefile = self.bundle = exchange.readbundle(ui, f, bundlename)
 
         if isinstance(self.bundle, bundle2.unbundle20):
-            cgparts = [part for part in self.bundle.iterparts()
-                       if (part.type == 'changegroup')
-                       and (part.params.get('version', '01')
-                            in changegroup.packermap)]
+            cgstream = None
+            for part in self.bundle.iterparts():
+                if part.type == 'changegroup':
+                    if cgstream is not None:
+                        raise NotImplementedError("can't process "
+                                                  "multiple changegroups")
+                    cgstream = part
+                    version = part.params.get('version', '01')
+                    if version not in changegroup.packermap:
+                        msg = _('Unsupported changegroup version: %s')
+                        raise error.Abort(msg % version)
+                    if self.bundle.compressed():
+                        cgstream = _writetempbundle(part.read,
+                                                    ".cg%sun" % version)
 
-            if not cgparts:
+            if cgstream is None:
                 raise error.Abort('No changegroups found')
-            version = cgparts[0].params.get('version', '01')
-            cgparts = [p for p in cgparts
-                       if p.params.get('version', '01') == version]
-            if len(cgparts) > 1:
-                raise NotImplementedError("Can't process multiple changegroups")
-            part = cgparts[0]
+            cgstream.seek(0)
 
-            part.seek(0)
-            self.bundle = changegroup.packermap[version][1](part, 'UN')
+            self.bundle = changegroup.packermap[version][1](cgstream, 'UN')
 
         elif self.bundle.compressed():
             f = _writetempbundle(self.bundle.read, '.hg10un', header='HG10UN')