alias: fixes exception when displaying translated help text

__doc__ of aliased command shouldn't cointain non-ASCII characters,
because it'll be gettext-ed later by commands.help_().
Here gettext can raise UnicodeDecodeError.

Once concatenated two translatable strings into one, it become untranslatable.
So this patch moves 'alias for:' from dispatch.cmdalias to commands.help_,
where help texts are translated.

'alias for:' was introduced by 6e8a16dd3e30.

mercurial/commands.py

@@ -1544,6 +1544,8 b' def help_(ui, name=None, with_version=Fa'
         doc = gettext(entry[0].__doc__)
         if not doc:
             doc = _("(no help text available)")
+        if hasattr(entry[0], 'definition'):  # aliased command
+            doc = _('alias for: hg %s\n\n%s') % (entry[0].definition, doc)
         if ui.quiet:
             doc = doc.splitlines()[0]
         keep = ui.verbose and ['verbose'] or []

mercurial/dispatch.py

@@ -208,8 +208,7 b' class cmdalias(object):'
             if self.help.startswith("hg " + cmd):
                 # drop prefix in old-style help lines so hg shows the alias
                 self.help = self.help[4 + len(cmd):]
-            self.__doc__ = _("alias for: hg %s\n\n%s") \
-                               % (definition, self.fn.__doc__)
+            self.__doc__ = self.fn.__doc__
 
         except error.UnknownCommand:
             def fn(ui, *args):