# HG changeset patch
# User Vadim Gelfer <vadim.gelfer@gmail.com>
# Date 1142059379 28800
# Node ID c0320567931f610c4a94032f54407cbdbe3fd163
# Parent  05c7d75be9256c1575d20b9a7f886422877fdb9a
merge util.esystem and util.system.


diff --git a/mercurial/localrepo.py b/mercurial/localrepo.py
--- a/mercurial/localrepo.py
+++ b/mercurial/localrepo.py
@@ -55,7 +55,7 @@ class localrepository(object):
         def runhook(name, cmd):
             self.ui.note(_("running hook %s: %s\n") % (name, cmd))
             env = dict([('HG_' + k.upper(), v) for k, v in args.iteritems()])
-            r = util.esystem(cmd, environ=env, cwd=self.root)
+            r = util.system(cmd, environ=env, cwd=self.root)
             if r:
                 desc, r = util.explain_exit(r)
                 if throw:
diff --git a/mercurial/ui.py b/mercurial/ui.py
--- a/mercurial/ui.py
+++ b/mercurial/ui.py
@@ -209,7 +209,9 @@ class ui(object):
                   os.environ.get("EDITOR", "vi"))
 
         os.environ["HGUSER"] = self.username()
-        util.system("%s \"%s\"" % (editor, name), errprefix=_("edit failed"))
+        util.system("%s \"%s\"" % (editor, name),
+                    environ={'HGUSER': self.username()},
+                    onerr=util.Abort, errprefix=_("edit failed"))
 
         t = open(name).read()
         t = re.sub("(?m)^HG:.*\n", "", t)
diff --git a/mercurial/util.py b/mercurial/util.py
--- a/mercurial/util.py
+++ b/mercurial/util.py
@@ -315,19 +315,13 @@ def _matcher(canonroot, cwd, names, inc,
                          (files and filematch(fn)))),
             (inc or exc or (pats and pats != [('glob', '**')])) and True)
 
-def system(cmd, errprefix=None):
-    """execute a shell command that must succeed"""
-    rc = os.system(cmd)
-    if rc:
-        errmsg = "%s %s" % (os.path.basename(cmd.split(None, 1)[0]),
-                            explain_exit(rc)[0])
-        if errprefix:
-            errmsg = "%s: %s" % (errprefix, errmsg)
-        raise Abort(errmsg)
+def system(cmd, environ={}, cwd=None, onerr=None, errprefix=None):
+    '''enhanced shell command execution.
+    run with environment maybe modified, maybe in different dir.
 
-def esystem(cmd, environ={}, cwd=None):
-    '''enhanced shell command execution.
-    run with environment maybe modified, maybe in different dir.'''
+    if command fails and onerr is None, return status.  if ui object,
+    print error message and return status, else raise onerr object as
+    exception.'''
     oldenv = {}
     for k in environ:
         oldenv[k] = os.environ.get(k)
@@ -338,7 +332,17 @@ def esystem(cmd, environ={}, cwd=None):
             os.environ[k] = str(v)
         if cwd is not None and oldcwd != cwd:
             os.chdir(cwd)
-        return os.system(cmd)
+        rc = os.system(cmd)
+        if rc and onerr:
+            errmsg = '%s %s' % (os.path.basename(cmd.split(None, 1)[0]),
+                                explain_exit(rc)[0])
+            if errprefix:
+                errmsg = '%s: %s' % (errprefix, errmsg)
+            try:
+                onerr.warn(errmsg + '\n')
+            except AttributeError:
+                raise onerr(errmsg)
+        return rc
     finally:
         for k, v in oldenv.iteritems():
             if v is None: