cmdstate: introduce a "saver" contextmanager and use it in place of save()
Previously, the state was only saved in some paths out of these functions. This
can be problematic, if the user ctrl-c's (or `kill -9`'s) the process, or we
exit out of `relocate` for anything besides the "expected" reason, we won't
record that we were in the middle of an evolve.
One of our users has discovered that this leaves hg in a weird state; the user
did something like this:
```
$ hg evolve
<something goes wrong with the merge tool, hits ctrl-c>
<deals with the merge conflicts>
$ hg evolve --continue
abort: no interrupted evolve to continue
$ hg evolve
abort: uncommitted changes
# Note: commands.status.verbose=True is set.
$ hg status
M foo
# The repository is in an unfinished *update* state.
# No unresolved merge conflicts
# To continue: hg update
```
The user did an `hg update`, but it didn't actually do anything besides take it
out of the unfinished update state (the files were still dirty in the working
directory).
$ cat >> $HGRCPATH <<EOF
> [defaults]
> amend=-d "0 0"
> [ui]
> ssh=python "$RUNTESTDIR/dummyssh"
> [phases]
> publish = False
> [extensions]
> EOF
$ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
$ mkcommit() {
> echo "$1" > "$1"
> hg add "$1"
> hg ci -m "add $1"
> }
setup repo
$ hg init server
$ hg clone ssh://user@dummy/server client
no changes found
updating to branch default
0 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ cp -r client other
Smoke testing
===============
$ cd client
$ mkcommit 0
$ mkcommit a
$ hg push
pushing to ssh://user@dummy/server
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 2 changesets with 2 changes to 2 files
$ hg pull
pulling from ssh://user@dummy/server
searching for changes
no changes found
$ hg pull -R ../other
pulling from ssh://user@dummy/server
requesting all changes
adding changesets
adding manifests
adding file changes
added 2 changesets with 2 changes to 2 files
new changesets 8685c6d34325:4957bfdac07e (2 drafts)
(run 'hg update' to get a working copy)
$ hg push -R ../other
pushing to ssh://user@dummy/server
searching for changes
no changes found
[1]
Push
=============
$ echo 'A' > a
$ hg amend
$ hg push
pushing to ssh://user@dummy/server
searching for changes
remote: adding changesets
remote: adding manifests
remote: adding file changes
remote: added 1 changesets with 1 changes to 1 files (+1 heads)
remote: 1 new obsolescence markers
remote: obsoleted 1 changesets
$ hg push
pushing to ssh://user@dummy/server
searching for changes
no changes found
[1]
Pull
=============
$ hg -R ../other pull
pulling from ssh://user@dummy/server
searching for changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 1 changes to [12] files \(\+1 heads\) (re)
1 new obsolescence markers
obsoleted 1 changesets
new changesets 9d1c114e7797 (1 drafts)
(run 'hg heads' to see heads)
$ hg -R ../other pull
pulling from ssh://user@dummy/server
searching for changes
no changes found
$ cd ..