Add core copy detection algorithm
This adds findcopies, which detects merge-relevant copies between
files in a pair of manifests back to the merge ancestor.
While the merge code invokes the copy detection routine, it does not
yet use the result.
checkout
2 files updated, 0 files merged, 2 files removed, 0 files unresolved
merge
resolving manifests
overwrite None branchmerge True partial False
ancestor f26ec4fc3fa3 local 8e765a822af2 remote af1939970a1c
b: remote created -> g
b2: remote created -> g
getting b
getting b2
2 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
blahblah
foo