Add $HGEDITOR hook and example script

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

Add $HGEDITOR hook and example script

This hook makes signing commits easier.

manifest hash: ba8723e4b52323528dfa681a58658a5b4b2c02e4
-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.0 (GNU/Linux)

iD8DBQFCmONFywK+sNU5EO8RAj87AKCEa5r9EepdYPiYRGo/jAjjwCIcVACfeBPe
QDInXr7karo6/P8d2bM/tVU=
=rxIQ
-----END PGP SIGNATURE-----

hgeditor

@@ -0,0 +1,21
+#!/bin/bash
+#
+# This is an example of using HGEDITOR to automate the signing of
+# commits and so on.
+
+MANIFEST=`grep '^HG: manifest hash' $1 | cut -b 19-`
+if grep -q "^HG: merge resolve" $1 ; then
+    # we don't sign merges
+    $EDITOR $1
+else
+    T=`mktemp`
+    CHANGED=`grep '^HG: changed' $1 | cut -b 13-`
+    # show a diff so writing commit comments is easier
+    hg diff $CHANGED >> $T
+    echo -e "\n\nmanifest hash: $MANIFEST" > $1
+    emacs -nw $T $1 
+    head -1 $1 > $T
+    echo >> $T
+    gpg -a -u $HGUSER -o - --clearsign $1 >> $T
+    mv $T $1
+fi

mercurial/hg.py

@@ -893,8 +893,9 class ui:
         f.write(text)
         f.close()
 
-        editor = os.environ.get("EDITOR", "vi")
+        editor = os.environ.get("HGEDITOR") or os.environ.get("EDITOR", "vi")
         r = os.system("%s %s" % (editor, name))
+
         if r:
             raise "Edit failed!"
 
@@ -903,7 +904,6 class ui:
 
         return t
 
-    
 class httprangereader:
     def __init__(self, url):
         self.url = url