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
> [extensions]
> EOF
$ echo "evolve=$(echo $(dirname $TESTDIR))/hgext3rd/evolve/" >> $HGRCPATH
$ hg init alpha
$ cd alpha
$ echo foo > foo
$ hg addremove
adding foo
$ hg ci -m 'foo'
$ for x in 1 2 3 4 ; do
> echo foo $x > foo
> hg amend
> done
Test conversion between obsolete marker formats
$ hg debugobsolete
e63c23eaa88ae77967edcf4ea194d31167c478b0 b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 0 (*) {'ef1': '*', 'user': 'test'} (glob)
b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 384fc811182687231962e486f23ea8c5bab7a2d3 0 (*) {'ef1': '*', 'user': 'test'} (glob)
384fc811182687231962e486f23ea8c5bab7a2d3 949d379b3c3bf051906bc3528c049cb536e2ec86 0 (*) {'ef1': '*', 'user': 'test'} (glob)
949d379b3c3bf051906bc3528c049cb536e2ec86 f2e4c45b2a4a58ccf7ef6825b8fa5685873cd2f7 0 (*) {'ef1': '*', 'user': 'test'} (glob)
$ hg debugobsconvert --new-format 0
Old store is version 1, will rewrite in version 0
Done!
$ hg debugobsolete
e63c23eaa88ae77967edcf4ea194d31167c478b0 b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 0 (*) {'ef1': '*', 'user': 'test'} (glob)
b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 384fc811182687231962e486f23ea8c5bab7a2d3 0 (*) {'ef1': '*', 'user': 'test'} (glob)
384fc811182687231962e486f23ea8c5bab7a2d3 949d379b3c3bf051906bc3528c049cb536e2ec86 0 (*) {'ef1': '*', 'user': 'test'} (glob)
949d379b3c3bf051906bc3528c049cb536e2ec86 f2e4c45b2a4a58ccf7ef6825b8fa5685873cd2f7 0 (*) {'ef1': '*', 'user': 'test'} (glob)
$ hg debugobsconvert --new-format 0
abort: New format is the same as the old format, not upgrading!
[255]
$ hg debugobsolete
e63c23eaa88ae77967edcf4ea194d31167c478b0 b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 0 (*) {'ef1': '*', 'user': 'test'} (glob)
b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 384fc811182687231962e486f23ea8c5bab7a2d3 0 (*) {'ef1': '*', 'user': 'test'} (glob)
384fc811182687231962e486f23ea8c5bab7a2d3 949d379b3c3bf051906bc3528c049cb536e2ec86 0 (*) {'ef1': '*', 'user': 'test'} (glob)
949d379b3c3bf051906bc3528c049cb536e2ec86 f2e4c45b2a4a58ccf7ef6825b8fa5685873cd2f7 0 (*) {'ef1': '*', 'user': 'test'} (glob)
$ hg debugobsconvert --new-format 1
Old store is version 0, will rewrite in version 1
Done!
$ hg debugobsolete
e63c23eaa88ae77967edcf4ea194d31167c478b0 b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 0 (*) {'ef1': '*', 'user': 'test'} (glob)
b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 384fc811182687231962e486f23ea8c5bab7a2d3 0 (*) {'ef1': '*', 'user': 'test'} (glob)
384fc811182687231962e486f23ea8c5bab7a2d3 949d379b3c3bf051906bc3528c049cb536e2ec86 0 (*) {'ef1': '*', 'user': 'test'} (glob)
949d379b3c3bf051906bc3528c049cb536e2ec86 f2e4c45b2a4a58ccf7ef6825b8fa5685873cd2f7 0 (*) {'ef1': '*', 'user': 'test'} (glob)
Test that the default is some reasonably modern format (first downgrade)
$ hg debugobsconvert --new-format 0
Old store is version 1, will rewrite in version 0
Done!
$ hg debugobsconvert
Old store is version 0, will rewrite in version 1
Done!
$ hg debugobsolete
e63c23eaa88ae77967edcf4ea194d31167c478b0 b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 0 (*) {'ef1': '*', 'user': 'test'} (glob)
b81ac6b9d2a55f9a7a6b90a006b1aab0568d6d34 384fc811182687231962e486f23ea8c5bab7a2d3 0 (*) {'ef1': '*', 'user': 'test'} (glob)
384fc811182687231962e486f23ea8c5bab7a2d3 949d379b3c3bf051906bc3528c049cb536e2ec86 0 (*) {'ef1': '*', 'user': 'test'} (glob)
949d379b3c3bf051906bc3528c049cb536e2ec86 f2e4c45b2a4a58ccf7ef6825b8fa5685873cd2f7 0 (*) {'ef1': '*', 'user': 'test'} (glob)