tests/test-double-merge.out

verify: fix "missing revlog!" errors for revlog format v0 and add test

With revlog format v0 the .d files are empty if the only revision stored is an
empty file. Since Mercurial can no longer create format v0 repositories, but
still use it, add a script which creates a repository with a single empty file.
This can be used in other tests if wanted.

created new head
changeset:   1:d9da848d0adf
user:        test
date:        Mon Jan 12 13:46:40 1970 +0000
summary:     cp foo bar; change both

  searching for copies back to rev 1
  unmatched files in other:
   bar
  all copies found (* = to merge, ! = divergent):
   bar -> foo *
  checking for directory renames
resolving manifests
 overwrite None partial False
 ancestor 310fd17130da local 2092631ce82b+ remote d9da848d0adf
 foo: versions differ -> m
 foo: remote copied to bar -> m
preserving foo for resolve of bar
preserving foo for resolve of foo
updating: foo 1/2 files (50.00%)
picked tool 'internal:merge' for bar (binary False symlink False)
merging foo and bar to bar
my bar@2092631ce82b+ other bar@d9da848d0adf ancestor foo@310fd17130da
 premerge successful
updating: foo 2/2 files (100.00%)
picked tool 'internal:merge' for foo (binary False symlink False)
merging foo
my foo@2092631ce82b+ other foo@d9da848d0adf ancestor foo@310fd17130da
 premerge successful
0 files updated, 2 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
-- foo --
line 0
line 1
line 2-1
-- bar --
line 0
line 1
line 2-2