resolve: report no argument warning using a hint

With this change resolve and revert produce consistent output when run with no
arguments:

$ hg resolve
abort: no files or directories specified
(use --all to remerge all files)

$ hg revert
abort: no files or directories specified
(use --all to revert all files)

mercurial/commands.py

@@ -4994,8 +4994,8 b' def resolve(ui, repo, *pats, **opts):'
     if pats and all:
         raise util.Abort(_("can't specify --all and patterns"))
     if not (all or pats or show or mark or unmark):
-        raise util.Abort(_('no files or directories specified; '
-                           'use --all to remerge all files'))
+        raise util.Abort(_('no files or directories specified'),
+                         hint=('use --all to remerge all files'))
 
     wlock = repo.wlock()
     try:

tests/test-merge9.t

@@ -76,7 +76,8 b' after resolve'
 
 resolve all warning
   $ hg resolve
-  abort: no files or directories specified; use --all to remerge all files
+  abort: no files or directories specified
+  (use --all to remerge all files)
   [255]
 
 resolve all