That's a bug. Emacs' process has the wrong pgid when its parent isn't an
interactive shell. Here's a workaround for the same problem using Git. I
would hope you can configure Mercurial similarly.

http://static.matthewlmcclure.com/n/

Emacs C-g Kills `git commit` On Mac OS X
2012-02-22

Workaround: Invoke Emacs via an interactive Bash shell.

emacs.sh:


    #! /bin/bash -i

    emacs "$@"


In a shell:


    git config --global core.editor emacs.sh


See also:

   - http://thread.gmane.org/gmane.comp.version-control.git/158981
   - http://www.cons.org/cracauer/sigint.html


Matt McClure
http://matthewlmcclure.com
http://www.mapmyfitness.com/profile/matthewlmcclure

On May 21, 2012, at 9:54 AM, Roy Smith <roy@panix.com> wrote:

I'm running:

GNU Emacs 22.1.1
OSX-10.6.8
Mercurial Distributed SCM (version 1.6.4+20101001)

If I do "hg commit", emacs is run as I would expect, but if I type a
Control-G, I get an "interrupted!" message, and emacs quits (leaving the
terminal modes unrestored).

Running ps shows that the command being executed is:

   emacs -nw
/var/folders/p5/p5Gj6NRtF-yAXT+X0YVgJU+++TM/-Tmp-/hg-editor-wQEeGG.txt

If I run that manually, I get normal operation.  I assume there's something
funky about the environment in which emacs is being executed, but I can't
figure out what that might be.  Any ideas?

It doesn't seem to be related to the buffer; I get the same problem in
other buffers.  M-X make command summary shows, for both the normal and
broken situations:

   C-g             keyboard-quit            <JISX0208>
    self-insert-command

--
Roy Smith
roy@panix.com