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.
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init a
$ cd a
$ echo a > a
$ hg ci -Ama
adding a
$ hg qnew a.patch
$ echo a >> a
$ hg qrefresh
$ hg qnew b.patch
$ echo b > b
$ hg add b
$ hg qrefresh
$ hg qnew c.patch
$ echo c > c
$ hg add c
$ hg qrefresh
$ hg qgoto a.patch
popping c.patch
popping b.patch
now at: a.patch
$ hg qgoto c.patch
applying b.patch
applying c.patch
now at: c.patch
$ hg qgoto b.patch
popping c.patch
now at: b.patch
Using index:
$ hg qgoto 0
popping b.patch
now at: a.patch
$ hg qgoto 2
applying b.patch
applying c.patch
now at: c.patch
No warnings when using index ... and update from non-qtip and with pending
changes in unrelated files:
$ hg qnew bug314159
$ echo d >> c
$ hg qrefresh
$ hg qnew bug141421
$ echo e >> b
$ hg qrefresh
$ hg up -r bug314159
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ echo f >> a
$ echo f >> b
$ echo f >> c
$ hg qgoto 1
abort: local changes found, qrefresh first
[255]
$ hg qgoto 1 -f
popping bug141421
popping bug314159
popping c.patch
now at: b.patch
$ hg st
M a
M b
? c.orig
$ hg up -qCr.
$ hg qgoto 3
applying c.patch
applying bug314159
now at: bug314159
Detect ambiguous non-index:
$ hg qgoto 14
patch name "14" is ambiguous:
bug314159
bug141421
abort: patch 14 not in series
[255]
$ cd ..