localrepo: stop doing special dirstate backup at transaction open
Since the dirstate writes are already managed by the transaction, we already do
a backup of the dirstate when necessary (and even trigger one to keep `hg
rollback` happy).
We needs some special code to deal with the initial empty checkout, but it is
not too complicated.
Managing variable filename (as dirstate-v2 uses) at the "journalfile" level, is
complex and fragile (which is consistent with the fact these files are not
journal…). If we no longer do it, our life is significantly simpler.
In some sense, we apply the xkcd-1134¹ solution to our savebackup/restorebackup
problem.
[1] https://xkcd.com/1134/
(the change to test-hardlink are expect as decreasing the number of duplicated
backup drive the hardlink count down)
$ cat >> $HGRCPATH << EOF
> [extensions]
> absorb=
> EOF
$ hg init repo1
$ cd repo1
Make some commits:
$ for i in 1 2 3; do
> echo $i >> a
> hg commit -A a -m "commit $i" -q
> done
absorb --edit-lines will run the editor if filename is provided:
$ hg absorb --edit-lines
nothing applied
[1]
$ HGEDITOR=cat hg absorb --edit-lines a
HG: editing a
HG: "y" means the line to the right exists in the changeset to the top
HG:
HG: /---- 4ec16f85269a commit 1
HG: |/--- 5c5f95224a50 commit 2
HG: ||/-- 43f0a75bede7 commit 3
HG: |||
yyy : 1
yy : 2
y : 3
nothing applied
[1]
Edit the file using --edit-lines:
$ cat > editortext << EOF
> y : a
> yy : b
> y : c
> yy : d
> y y : e
> y : f
> yyy : g
> EOF
$ HGEDITOR='cat editortext >' hg absorb -q --edit-lines a
$ hg cat -r 0 a
d
e
f
g
$ hg cat -r 1 a
b
c
d
g
$ hg cat -r 2 a
a
b
e
g