mq: new commands qselect, qguard
implement quilt-style guards for mq.
guards allow to control whether patch can be pushed.
if guard X is active and patch is guarded by +X (called "posative guard"),
patch can be pushed. if patch is guarded by -X (called "nagative guard"),
patch cannot be pushed and is skipped.
use qguard to set/list guards on patches. use qselect to set/list
active guards.
also "qseries -v" prints guarded patches with "G" now.
#!/bin/sh
hg init a
echo a > a/a
hg --cwd a ci -A -m a
hg clone a b
echo b > b/b
hg --cwd b ci -A -m b
chmod 100 a/.hg
hg --cwd b push ../a
chmod 700 a/.hg