Correct optimization from 3464f5e77f34; add a test.
If there are two (or more) heads that point to the same .hgtags
node, we can safely skip parsing the file in all but the last head.
(In 3464f5e77f34, we were parsing the file in the first head and
skipping all the others.)
adding foo
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
checking changesets
checking manifests
crosschecking files in changesets and manifests
checking files
1 files, 1 changesets, 1 total revisions
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
foo
2ed2a3912a0b24502043eae84ee4b279c18b90dd 644 foo
pulling from http://localhost:20059/
searching for changes
no changes found