cmdstate: avoid setting a default argument to a mutable object (`{}`)
If there's ever more than one cmdstate for the lifetime of the process, this can
cause surprising behavior where the later cmdstates pick up options from the
earlier ones.
I've not seen any evidence this is actually causing any issues, but it's subtle
enough that it should probably be fixed to help save significant debugging time
later.
testing topic with shelve extension
------------------------------------
$ . "$TESTDIR/testlib/topic_setup.sh"
$ hg init repo
$ cd repo
$ cat <<EOF >>.hg/hgrc
> [extensions]
> shelve=
> EOF
$ touch a
$ echo "Hello" >> a
$ hg topic "testing-shelve"
marked working directory as topic: testing-shelve
$ hg topic
* testing-shelve (0 changesets)
$ hg ci -m "First commit" -A
adding a
active topic 'testing-shelve' grew its first changeset
(see 'hg help topics' for more information)
$ hg topic
* testing-shelve (1 changesets)
$ echo " World" >> a
$ hg stack
### topic: testing-shelve
### target: default (branch)
s1@ First commit (current)
shelve test
-----------
$ hg shelve
shelved as default
1 files updated, 0 files merged, 0 files removed, 0 files unresolved
$ hg topic
* testing-shelve (1 changesets)
$ hg stack
### topic: testing-shelve
### target: default (branch)
s1@ First commit (current)
unshelve test
-------------
$ hg unshelve
unshelving change 'default'
$ hg topic
* testing-shelve (1 changesets)
$ hg stack
### topic: testing-shelve
### target: default (branch)
s1@ First commit (current)