subrepo: add dirtyreason to centralize composing dirty reason message

This patch newly adds "dirtyreason()" to centralize composing dirty
reason message like "uncommitted changes in subrepository 'xxxx'".

There are 3 similar messages below, and this patch is a part of
preparations for unifying them into (1), too.

  1. uncommitted changes in subrepository 'XXXX'
  2. uncommitted changes in subrepository XXXX
  3. uncommitted changes in subrepo XXXX

This patch chooses adding new method "dirtyreason()" instead of making
"dirty()" return "reason string", because:

  - some of existing "dirty()" implementation is too complicated to do
    so simply, and

  - ill-mannered 3rd party subrepo classes, of which "dirty()" doesn't
    return "reason string", cause meaningless message (even though it
    is rare case)

mercurial/localrepo.py

@@ -1372,10 +1372,10 b' class localrepository(object):'
                         if not force:
                             raise util.Abort(
                                 _("commit with new subrepo %s excluded") % s)
-                    if wctx.sub(s).dirty(True):
+                    dirtyreason = wctx.sub(s).dirtyreason(True)
+                    if dirtyreason:
                         if not self.ui.configbool('ui', 'commitsubrepos'):
-                            raise util.Abort(
-                                _("uncommitted changes in subrepo %s") % s,
+                            raise util.Abort(dirtyreason,
                                 hint=_("use --subrepos for recursive commit"))
                         subs.append(s)
                         commitsubs.add(s)

mercurial/subrepo.py

@@ -390,6 +390,18 b' class abstractsubrepo(object):'
         """
         raise NotImplementedError
 
+    def dirtyreason(self, ignoreupdate=False):
+        """return reason string if it is ``dirty()``
+
+        Returned string should have enough information for the message
+        of exception.
+
+        This returns None, otherwise.
+        """
+        if self.dirty(ignoreupdate=ignoreupdate):
+            return _("uncommitted changes in subrepository '%s'"
+                     ) % subrelpath(self)
+
     def basestate(self):
         """current working directory base state, disregarding .hgsubstate
         state and working directory modifications"""

tests/test-largefiles-misc.t

@@ -248,7 +248,7 b' verify that large files in subrepos hand'
   commit: 1 subrepos
   update: (current)
   $ hg ci -m "this commit should fail without -S"
-  abort: uncommitted changes in subrepo subrepo
+  abort: uncommitted changes in subrepository 'subrepo'
   (use --subrepos for recursive commit)
   [255]
 

tests/test-subrepo-recursion.t

@@ -59,7 +59,7 b' Test recursive diff without committing a'
 Commits:
 
   $ hg commit -m fails
-  abort: uncommitted changes in subrepo foo
+  abort: uncommitted changes in subrepository 'foo'
   (use --subrepos for recursive commit)
   [255]
 

tests/test-subrepo.t

@@ -146,7 +146,7 b' leave sub dirty (and check ui.commitsubr'
 
   $ echo c > s/a
   $ hg --config ui.commitsubrepos=no ci -m4
-  abort: uncommitted changes in subrepo s
+  abort: uncommitted changes in subrepository 's'
   (use --subrepos for recursive commit)
   [255]
   $ hg id