revlogv2: make sure bundling pick a compatible bundle format

Before this change, revlog-v2 repository where bundled using the incompatible
"v1" format.

Differential Revision: https://phab.mercurial-scm.org/D10802

mercurial/bundlecaches.py

@@ -167,6 +167,8 b' def parsebundlespec(repo, spec, strict=T'
             # Generaldelta repos require v2.
             if requirementsmod.GENERALDELTA_REQUIREMENT in repo.requirements:
                 version = b'v2'
+            elif requirementsmod.REVLOGV2_REQUIREMENT in repo.requirements:
+                version = b'v2'
             # Modern compression engines require v2.
             if compression not in _bundlespecv1compengines:
                 version = b'v2'

tests/test-revlog-v2.t

@@ -69,6 +69,14 b' Header written as expected'
   .hg/store/data/foo.i:
   0000: 00 00 de ad                                     |....|
 
+Bundle use a compatible changegroup format
+------------------------------------------
+
+  $ hg bundle --all ../basic.hg
+  1 changesets found
+  $ hg debugbundle --spec ../basic.hg
+  bzip2-v2
+
 The expected files are generated
 --------------------------------