push: obsolete rather than rebase & strip when enabled This requires a few changes to wrappers.push() to use obsolescence rather than strip and to make the rebase -- which is non-destructive with obsolete active -- to no longer keep the originals. Possible future work involves no longer relying on rebase for non-outgoing revisions, and simply leaving them in the troubled state. We test this feature by adding setting obsolete_mode_tests to True in classes that push changes.

--- a/tests/test_push_dirs.py
+++ b/tests/test_push_dirs.py
@@ -3,6 +3,8 @@ import test_util
 import unittest
 
 class TestPushDirectories(test_util.TestBase):
+    obsolete_mode_tests = True
+
     def test_push_dirs(self):
         repo_path = self.load_and_fetch('emptyrepo.svndump')[1]