histedit: use ui.fin to read commands from stdin

stdin is wrapped by channeledinput in command-server session.

hgext/histedit.py

@@ -173,7 +173,6 b' from __future__ import absolute_import'
 
 import errno
 import os
-import sys
 
 from mercurial.i18n import _
 from mercurial import (
@@ -991,9 +990,9 b' def _getgoal(opts):'
         return goaleditplan
     return goalnew
 
-def _readfile(path):
+def _readfile(ui, path):
     if path == '-':
-        return sys.stdin.read()
+        return ui.fin.read()
     else:
         with open(path, 'rb') as f:
             return f.read()
@@ -1191,7 +1190,7 b' def _edithisteditplan(ui, repo, state, r'
                                  node.short(state.topmost))
         rules = ruleeditor(repo, ui, state.actions, comment)
     else:
-        rules = _readfile(rules)
+        rules = _readfile(ui, rules)
     actions = parserules(rules, state)
     ctxs = [repo[act.node] \
             for act in state.actions if act.node]
@@ -1232,7 +1231,7 b' def _newhistedit(ui, repo, state, revs, '
         actions = [pick(state, r) for r in revs]
         rules = ruleeditor(repo, ui, actions, comment)
     else:
-        rules = _readfile(rules)
+        rules = _readfile(ui, rules)
     actions = parserules(rules, state)
     warnverifyactions(ui, repo, actions, state, ctxs)
 

tests/test-commandserver.t

@@ -135,6 +135,19 b' typical client does not want echo-back m'
   summary:     1
   
 
+check that "histedit --commands=-" can read rules from the input channel:
+
+  >>> import cStringIO
+  >>> from hgclient import readchannel, runcommand, check
+  >>> @check
+  ... def serverinput(server):
+  ...     readchannel(server)
+  ...     rules = 'pick eff892de26ec\n'
+  ...     runcommand(server, ['histedit', '0', '--commands=-',
+  ...                         '--config', 'extensions.histedit='],
+  ...                input=cStringIO.StringIO(rules))
+  *** runcommand histedit 0 --commands=- --config extensions.histedit=
+
 check that --cwd doesn't persist between requests:
 
   $ mkdir foo