treemanifest: stop storing full path for each item in manifest._lazydirs
This information is obtainable, if needed, based on the lazydirs key (which is
the entry name) and the manifest's `dir()` method.
### Performance
This is actually both a memory and a performance improvement, but it's likely to
be a very small one in most situations. In the pathological repo I've been using
for testing other performance work I've done recently, this reduced the time for
a rebase operation (rebasing two commits across a public-phase change that
touches a sibling of one of my tracked directories where the common parent is
massive (>>10k entries)):
#### Before
```
Time (mean ± σ): 4.059 s ± 0.121 s [User: 0.9 ms, System: 0.6 ms]
Range (min … max): 3.941 s … 4.352 s 10 runs
```
#### After
```
Time (mean ± σ): 3.707 s ± 0.060 s [User: 0.8 ms, System: 0.8 ms]
Range (min … max): 3.648 s … 3.818 s 10 runs
```
Differential Revision: https://phab.mercurial-scm.org/D9553
#require execbit
b51a8138292a introduced a regression where we would mention in the
changelog executable files added by the second parent of a merge. Test
that that doesn't happen anymore
$ hg init repo
$ cd repo
$ echo foo > foo
$ hg ci -qAm 'add foo'
$ echo bar > bar
$ chmod +x bar
$ hg ci -qAm 'add bar'
manifest of p2:
$ hg manifest
bar
foo
$ hg up -qC 0
$ echo >> foo
$ hg ci -m 'change foo'
created new head
manifest of p1:
$ hg manifest
foo
$ hg merge
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
(branch merge, don't forget to commit)
$ chmod +x foo
$ hg ci -m 'merge'
this should not mention bar but should mention foo:
$ hg tip -v
changeset: 3:c53d17ff3380
tag: tip
parent: 2:ed1b79f46b9a
parent: 1:d394a8db219b
user: test
date: Thu Jan 01 00:00:00 1970 +0000
files: foo
description:
merge
$ hg debugindex bar
rev linkrev nodeid p1 p2
0 1 b004912a8510 000000000000 000000000000
$ cd ..