tests/test-branchmap.out

findrenames: Optimise "addremove -s100" by matching files by their SHA1 hashes.

We speed up 'findrenames' for the usecase when a user specifies they
want a similarity of 100% by matching files by their exact SHA1 hash
value. This reduces the number of comparisons required to find exact
matches from O(n^2) to O(n).

While it would be nice if we could just use mercurial's pre-calculated
SHA1 hash for existing files, this hash includes the file's ancestor
information making it unsuitable for our purposes. Instead, we calculate
the hash of old content from scratch.

The following benchmarks were taken on the current head of crew:

addremove 100% similarity:
  rm -rf *; hg up -C; mv tests tests.new
  hg --time addremove -s100 --dry-run

  before:  real 176.350 secs (user 128.890+0.000 sys 47.430+0.000)
  after:   real   2.130 secs (user   1.890+0.000 sys  0.240+0.000)

addremove 75% similarity:
  rm -rf *; hg up -C; mv tests tests.new; \
      for i in tests.new/*; do echo x >> $i; done
  hg --time addremove -s75  --dry-run

  before: real 264.560 secs (user 215.130+0.000 sys 49.410+0.000)
  after:  real 218.710 secs (user 172.790+0.000 sys 45.870+0.000)

marked working directory as branch æ
adding foo
listening at http://localhost/ (bound to 127.0.0.1)
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to 1 files
updating to branch æ
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
changeset:   0:867c11ce77b8
branch:      æ
tag:         tip
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     foo

pushing to http://localhost:PORT
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files
changeset:   1:58e7c90d67cb
branch:      æ
tag:         tip
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     bar

changeset:   0:867c11ce77b8
branch:      æ
user:        test
date:        Thu Jan 01 00:00:00 1970 +0000
summary:     foo

pushing to ssh://dummy/
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files