completion: add a debuglabelcomplete command
When completing a "label" (a symbolic name for a commit), the
bash_completion script currently has to invoke hg three times. For
a large repository, the cost of starting up and loading all the
necessary context over and over is very high.
For instance, in mozilla-central:
time (export HGPLAIN=1; hg tags -q; hg bookmarks -q; hg branches) >/dev/null
0.446 sec
Compare with the debuglabelcomplete command that this commit adds:
time hg debuglabelcomplete >/dev/null
0.148 sec
This greatly helps responsiveness.
run-tests: only sort files when not given as argument
os.listdir returns the files in any order. This has to be sorted.
But when given as argument, the user should be allowed to set any order.
This restores the behaviour before
9848a94e2a.