dispatch: replace mayberepr with shellquote

The quoting logic here was actually insufficient, and would have had
bogus b-prefixes on Python 3. shellquote seems more appropriate
anyway. Surprisingly, only two tests have output changes, and both of
them look reasonable to me (both are in blackbox logs).

Spotted by Yuya during review.

mercurial/dispatch.py

@@ -92,13 +92,8 b' def _formatparse(write, inst):'
     if inst.hint:
         write(_("(%s)\n") % inst.hint)
 
-def _mayberepr(a):
-    if ' ' in a:
-        return encoding.strtolocal(repr(a))
-    return a
-
 def _formatargs(args):
-    return ' '.join(_mayberepr(a) for a in args)
+    return ' '.join(util.shellquote(a) for a in args)
 
 def dispatch(req):
     "run the command specified in req.args"

tests/test-blackbox.t

@@ -25,7 +25,7 b' alias expansion is logged'
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> add a
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> add a exited 0 after * seconds (glob)
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000+ (5000)> blackbox
-  1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000+ (5000)> blackbox --config blackbox.dirty=True exited 0 after * seconds (glob)
+  1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000+ (5000)> blackbox --config 'blackbox.dirty=True' exited 0 after * seconds (glob)
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> confuse
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> alias 'confuse' expands to 'log --limit 3'
   1970/01/01 00:00:00 bob @0000000000000000000000000000000000000000 (5000)> confuse exited 0 after * seconds (glob)

tests/test-devel-warnings.t

@@ -139,7 +139,7 b''
   $ hg blackbox -l 9
   1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> devel-warn: revset "oldstyle" uses list instead of smartset
   (compatibility will be dropped after Mercurial-3.9, update your code.) at: *mercurial/revset.py:* (mfunc) (glob)
-  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> log -r oldstyle() -T {rev}\n exited 0 after * seconds (glob)
+  1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> log -r 'oldstyle()' -T '{rev}\n' exited 0 after * seconds (glob)
   1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> oldanddeprecated
   1970/01/01 00:00:00 bob @cb9a9f314b8b07ba71012fcdbc544b5a4d82ff5b (5000)> devel-warn: foorbar is deprecated, go shopping
   (compatibility will be dropped after Mercurial-42.1337, update your code.) at: $TESTTMP/buggylocking.py:* (oldanddeprecated) (glob)