branchcache: add a "pure topological head" fast path
In a narrow but actually quick common case, all topological heads are all on
the same branch and all open. In this case, computing the branch map is very
simple. We can quickly detect situation where this situation will not change.
So we update the V3 format to be able to express this situation and upgrade the
update code to detect we remains in that mode.
The branch cache is populated with the actual value when the branch map is
accessed, but the update_disk method can do the update without needing to
populate it.
#require bzr
$ . "$TESTDIR/bzr-definitions"
The file/directory replacement can only be reproduced on
bzr >= 1.4. Merge it back in test-convert-bzr-directories once
this version becomes mainstream.
replace file with dir
$ mkdir test-replace-file-with-dir
$ cd test-replace-file-with-dir
$ brz init -q source
$ cd source
$ echo d > d
$ brz add -q d
$ brz commit -q -m 'add d file'
$ rm d
$ mkdir d
$ brz add -q d
$ brz commit -q -m 'replace with d dir'
$ echo a > d/a
$ brz add -q d/a
$ brz commit -q -m 'add d/a'
$ cd ..
$ hg convert source source-hg
initializing destination source-hg repository
scanning source...
sorting...
converting...
2 add d file
1 replace with d dir
0 add d/a
$ manifest source-hg tip
% manifest of tip
644 d/a
$ cd source-hg
$ hg update
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cd ../..