zsh_completion: declare appropriate local parameters for ->string form
When ->string form is used for _arguments, the function that calls it must
declare appropriate local parameters.
Managing local return value is needed to tell the completion system if our
function succeeded in suggesting something or not, plus without that `hg diff
-<TAB>` doesn't look right.
While at it, fix a copypaste error (s/diff_files/revert_files/).
Docs: http://zsh.sourceforge.net/Doc/Release/Completion-System.html
Differential Revision: https://phab.mercurial-scm.org/D4264
#require symlink
$ echo "[extensions]" >> $HGRCPATH
$ echo "mq=" >> $HGRCPATH
$ hg init
$ hg qinit
$ hg qnew base.patch
$ echo aaa > a
$ echo bbb > b
$ echo ccc > c
$ hg add a b c
$ hg qrefresh
$ readlink.py a
a -> a not a symlink
test replacing a file with a symlink
$ hg qnew symlink.patch
$ rm a
$ ln -s b a
$ hg qrefresh --git
$ readlink.py a
a -> b
$ hg qpop
popping symlink.patch
now at: base.patch
$ hg qpush
applying symlink.patch
now at: symlink.patch
$ readlink.py a
a -> b
test updating a symlink
$ rm a
$ ln -s c a
$ hg qnew --git -f updatelink
$ readlink.py a
a -> c
$ hg qpop
popping updatelink
now at: symlink.patch
$ hg qpush --debug
applying updatelink
patching file a
committing files:
a
committing manifest
committing changelog
updating the branch cache
now at: updatelink
$ readlink.py a
a -> c
$ hg st
test replacing a symlink with a file
$ ln -s c s
$ hg add s
$ hg qnew --git -f addlink
$ rm s
$ echo sss > s
$ hg qnew --git -f replacelinkwithfile
$ hg qpop
popping replacelinkwithfile
now at: addlink
$ hg qpush
applying replacelinkwithfile
now at: replacelinkwithfile
$ cat s
sss
$ hg st
test symlink removal
$ hg qnew removesl.patch
$ hg rm a
$ hg qrefresh --git
$ hg qpop
popping removesl.patch
now at: replacelinkwithfile
$ hg qpush
applying removesl.patch
now at: removesl.patch
$ hg st -c
C b
C c
C s
replace broken symlink with another broken symlink
$ ln -s linka linka
$ hg add linka
$ hg qnew link
$ hg mv linka linkb
$ rm linkb
$ ln -s linkb linkb
$ hg qnew movelink
$ hg qpop
popping movelink
now at: link
$ hg qpush
applying movelink
now at: movelink
$ readlink.py linkb
linkb -> linkb