addbranchrevs: explicitly detect the need to fetch a peer

Instead of having `peer()` method on all `peer()` for this usecase, we could
simply handle it explicitly.

mercurial/hg.py

@@ -66,7 +66,11 b" sharedbookmarks = b'bookmarks'"
 
 
 def addbranchrevs(lrepo, other, branches, revs):
-    peer = other.peer()  # a courtesy to callers using a localrepo for other
+    if util.safehasattr(other, 'peer'):
+        # a courtesy to callers using a localrepo for other
+        peer = other.peer()
+    else:
+        peer = other
     hashbranch, branches = branches
     if not hashbranch and not branches:
         x = revs or None