rebase: fix rebase with no common ancestors (issue4446) stable 3.2.1

rebase: fix rebase with no common ancestors (issue4446)

The new rebase revset didn't check for the case when there are no common
ancestors. Now it does. The new behavior should be the same as the pre-3.2
behavior. Added a test.

--- a/hgext/rebase.py	Thu Nov 06 10:57:13 2014 -0500
+++ b/hgext/rebase.py	Mon Nov 10 10:44:42 2014 -0800
@@ -274,8 +274,12 @@
                                 "can't compute rebase set\n"))
                     return 1
                 commonanc = repo.revs('ancestor(%ld, %d)', base, dest).first()
-                rebaseset = repo.revs('(%d::(%ld) - %d)::',
-                                      commonanc, base, commonanc)
+                if commonanc is not None:
+                    rebaseset = repo.revs('(%d::(%ld) - %d)::',
+                                          commonanc, base, commonanc)
+                else:
+                    rebaseset = []
+
                 if not rebaseset:
                     # transform to list because smartsets are not comparable to
                     # lists. This should be improved to honor lazyness of

--- a/tests/test-rebase-parameters.t	Thu Nov 06 10:57:13 2014 -0500
+++ b/tests/test-rebase-parameters.t	Mon Nov 10 10:44:42 2014 -0800
@@ -468,3 +468,17 @@
   [255]
 
   $ cd ..
+
+No common ancestor
+
+  $ hg init separaterepo
+  $ cd separaterepo
+  $ touch a
+  $ hg commit -Aqm a
+  $ hg up -q null
+  $ touch b
+  $ hg commit -Aqm b
+  $ hg rebase -d 0
+  nothing to rebase from d7486e00c6f1 to 3903775176ed
+  [1]
+  $ cd ..