[PATCH 4 of 7 v2] rebase: improve error message for empty --source set

[Mads Kiilerich]

# HG changeset patch
# User Mads Kiilerich <madski at unity3d.com>
# Date 1384730518 18000
#      Sun Nov 17 18:21:58 2013 -0500
# Node ID 3bff26f6716934d0c5257784e857af9c6dfb153c
# Parent  a259f7b488ab54d37ef1fd0574b583e2c63914fd
rebase: improve error message for empty --source set

Before, it just said 'nothing to rebase' in this case. Now, it aborts
mentioning the reason: 'empty "source" revision set'.

Specifying revisions that cannot be rebased is a 'soft' error, but specifying
an empty set deserves an abort that explains exactly what the problem is.

diff --git a/hgext/rebase.py b/hgext/rebase.py
--- a/hgext/rebase.py
+++ b/hgext/rebase.py
@@ -226,7 +226,11 @@ def rebase(ui, repo, **opts):
                                        'nothing to rebase'))
             elif srcf:
                 src = scmutil.revrange(repo, [srcf])
+                if not src:
+                    raise util.Abort(_('empty "source" revision set - '
+                                       'nothing to rebase'))
                 rebaseset = repo.revs('(%ld)::', src)
+                assert rebaseset
             else:
                 base = scmutil.revrange(repo, [basef or '.'])
                 rebaseset = repo.revs(
diff --git a/tests/test-rebase-parameters.t b/tests/test-rebase-parameters.t
--- a/tests/test-rebase-parameters.t
+++ b/tests/test-rebase-parameters.t
@@ -83,6 +83,10 @@ These fail:
   abort: empty "rev" revision set - nothing to rebase
   [255]
 
+  $ hg rebase --source '1 & !1'
+  abort: empty "source" revision set - nothing to rebase
+  [255]
+
   $ hg rebase
   nothing to rebase
   [1]