test: enforce v1 in 'test-debugbundle.t'

This test is about bundle1 and should remain so when we move to generaldelta by
default.

tests/test-debugbundle.t

@@ -6,7 +6,7 b' Create a test repository:'
   $ touch a ; hg add a ; hg ci -ma
   $ touch b ; hg add b ; hg ci -mb
   $ touch c ; hg add c ; hg ci -mc
-  $ hg bundle --base 0 --rev tip bundle.hg -v
+  $ hg bundle --base 0 --rev tip bundle.hg -v --type v1
   2 changesets found
   uncompressed size of bundle content:
        332 (changelog)