findincoming: do the binary search in branches in parallel

mercurial/localrepo.py

@@ -1343,10 +1343,11 b' class localrepository(repo.repository):'
                         unknown.append(b)
 
         # do binary search on the branches we found
+        search = [(t, b) for (t, b, p1, p2) in search]
         while search:
-            n = search.pop(0)
+            newsearch = []
             reqcnt += 1
-            l = remote.between([(n[0], n[1])])[0]
+            for n, l in zip(search, remote.between(search)):
             l.append(n[1])
             p = n[0]
             f = 1
@@ -1361,9 +1362,10 b' class localrepository(repo.repository):'
                     else:
                         self.ui.debug(_("narrowed branch search to %s:%s\n")
                                       % (short(p), short(i)))
-                        search.append((p, i))
+                            newsearch.append((p, i))
                     break
                 p, f = i, f * 2
+                search = newsearch
 
         # sanity check our fetch list
         for f in fetch.keys():