test: use generaldelta in test-manifestv2.t

Generaldelta and bundle2 have no real influence on this test. So we can safely
switch it early.

tests/test-manifestv2.t

@@ -1,5 +1,10 b''
 Create repo with old manifest
 
+  $ cat << EOF >> $HGRCPATH
+  > [format]
+  > usegeneraldelta=yes
+  > EOF
+
   $ hg init existing
   $ cd existing
   $ echo footext > foo
@@ -91,6 +96,6 b" Check that 'hg verify', which uses manif"
 Check that manifest revlog is smaller than for v1
 
   $ hg debugindex -m
-     rev    offset  length   base linkrev nodeid       p1           p2
-       0         0      81      0       0 57361477c778 000000000000 000000000000
+     rev    offset  length  delta linkrev nodeid       p1           p2
+       0         0      81     -1       0 57361477c778 000000000000 000000000000
        1        81      33      0       1 aeaab5a2ef74 57361477c778 000000000000