exthelper: support the option argument when registering a command

Largefiles uses this 5th argument with push and pull, so this will be tested in
the next commit.  I assume the reason for unrolling and reforming the tuple in
each finalxxxsetup() is to validate that something proper was passed in when
registering.  But it's better to explode when decorating than during the delayed
actual registration.

mercurial/exthelper.py

@@ -13,6 +13,7 b' from __future__ import absolute_import'
 
 from . import (
     commands,
+    error,
     extensions,
     registrar,
 )
@@ -80,8 +81,8 b' class exthelper(object):'
         for command, wrapper, opts in self._commandwrappers:
             entry = extensions.wrapcommand(commands.table, command, wrapper)
             if opts:
-                for short, long, val, msg in opts:
-                    entry[1].append((short, long, val, msg))
+                for opt in opts:
+                    entry[1].append(opt)
         for cont, funcname, wrapper in self._functionwrappers:
             extensions.wrapfunction(cont, funcname, wrapper)
         for c in self._uicallables:
@@ -121,8 +122,8 b' class exthelper(object):'
                 knownexts[ext] = e.cmdtable
             entry = extensions.wrapcommand(knownexts[ext], command, wrapper)
             if opts:
-                for short, long, val, msg in opts:
-                    entry[1].append((short, long, val, msg))
+                for opt in opts:
+                    entry[1].append(opt)
 
         for c in self._extcallables:
             c(ui)
@@ -206,12 +207,21 b' class exthelper(object):'
                 ui.note('Barry!')
                 return orig(ui, repo, *args, **kwargs)
 
-        The `opts` argument allows specifying additional arguments for the
-        command.
+        The `opts` argument allows specifying a list of tuples for additional
+        arguments for the command.  See ``mercurial.fancyopts.fancyopts()`` for
+        the format of the tuple.
 
         """
         if opts is None:
             opts = []
+        else:
+            for opt in opts:
+                if not isinstance(opt, tuple):
+                    raise error.ProgrammingError('opts must be list of tuples')
+                if len(opt) not in (4, 5):
+                    msg = 'each opt tuple must contain 4 or 5 values'
+                    raise error.ProgrammingError(msg)
+
         def dec(wrapper):
             if extension is None:
                 self._commandwrappers.append((command, wrapper, opts))