Problems with an own patch against Mercurial Queues

[Dr Rainer Woitok]

Greetings,

for quite some time I have applied the following little patch to Mercur-
ial, because I think a message containing the word "error" is in fact an
error message and should thus go to standard error:

$ cat .hg/patches/MqMessage | grep -v '^#"
Redirect error message from stdout to stderr.

diff --git a/hgext/mq.py b/hgext/mq.py
--- a/hgext/mq.py
+++ b/hgext/mq.py
@@ -1488,7 +1488,7 @@
             top = self.applied[-1].name
             if ret[0] and ret[0] > 1:
                 msg = _("errors during apply, please fix and qrefresh %s\n")
-                self.ui.write(msg % top)
+                self.ui.warn(msg % top)
             else:
                 self.ui.write(_("now at: %s\n") % top)
             return ret[0]
$

This patch  worked for me  until I recently  updated my  Mercurial clone
from  "https://www.mercurial-scm.org/repo/hg-stable".   After  that  the
message in question was sent to standard output  regardless of my patch,
even though the patch itself still applies cleanly.   From the perspect-
ive of my patch the "first bad" changeset is

$ hg log -r qparent -T '{node}'
27481162780894fb82e4b2f679f967a3a86cbc3b

while the "last good" changeset is

$ hg log -r qparent^ -T '{node}'
ee9243715c59c62c9a2619d7957f2dc159d1373b

While I can see  that this  "first bad" changeset  corrects some problem
with the pager,  it is not at all  clear to me  whether now ignoring the
change my patch introduces is a new bug or a new feature :-)

This is the script I'm using to test my patch:

$ cat ../Tests/mercurial/MqMessage.sh                                          
#! /bin/ksh

mkdir /tmp/test
cd    /tmp/test

export HGRCPATH=$PWD/.hgrc PS4=' $ '

set -x

cat > .hgrc <<EOF                   # Enable Mercurial Queues extension.
[extensions]
mq =
[ui]
color = no
EOF

hg init repo
cd      repo
echo a > file
hg com -Am File
cat file

hg init --mq
hg qnew p1                                             # Create patch 1.
echo 1 >| file
hg qrefresh
hg commit --mq -m p1
cat file

hg qpop
hg qnew p2                         # Create patch 2 in front of patch 1.
echo 2 >| file
hg qrefresh
hg commit --mq -m p2

hg qpush > out                # Try to apply patch 1, which should fail.
cat out

set +x
cd /tmp
rm -rf test
$

Running this script  with the  patch applied  on top of the  "last good"
changeset yields:

$ hg log -r qparent -T '{node}'
ee9243715c59c62c9a2619d7957f2dc159d1373b
$ ../Tests/mercurial/MqMessage.sh
 $ >.hgrc
 $ <<EOF
 $ cat
 $ hg init repo
 $ cd repo
 $ >file
 $ echo a
 $ hg com -Am File
adding file
 $ cat file
a
 $ hg init --mq
 $ hg qnew p1
 $ >|file
 $ echo 1
 $ hg qrefresh
 $ hg commit --mq -m p1
 $ cat file
1
 $ hg qpop
popping p1 patch queue now empty
 $ hg qnew p2
 $ >|file
 $ echo 2
 $ hg qrefresh
 $ hg commit --mq -m p2
 $ >out
 $ hg qpush
patching file file
Hunk #1 FAILED at 0
1 out of 1 hunks FAILED -- saving rejects to file file.rej
patch failed, unable to continue (try -v)
patch failed, rejects left in working directory
errors during apply, please fix and qrefresh p1
 $ cat out
applying p1
 $ set +x
$

As you can see above  the message in question did NOT go into file "out"
but was sent to standard error, as it should.

But running  the same test script  with the patch  applied on top of the
"first bad" changeset yields:

$ hg log -r qparent -T '{node}'
27481162780894fb82e4b2f679f967a3a86cbc3b
$ ../Tests/mercurial/MqMessage.sh
 $ >.hgrc 
 $ <<EOF 
 $ cat
 $ hg init repo
 $ cd repo
 $ >file 
 $ echo a
 $ hg com -Am File
adding file
 $ cat file
a
 $ hg init --mq
 $ hg qnew p1
 $ >|file 
 $ echo 1
 $ hg qrefresh
 $ hg commit --mq -m p1
 $ cat file
1
 $ hg qpop
popping p1
patch queue now empty
 $ hg qnew p2
 $ >|file 
 $ echo 2
 $ hg qrefresh
 $ hg commit --mq -m p2
 $ >out 
 $ hg qpush
patching file file
Hunk #1 FAILED at 0
1 out of 1 hunks FAILED -- saving rejects to file file.rej
patch failed, unable to continue (try -v)
patch failed, rejects left in working directory
 $ cat out
applying p1
errors during apply, please fix and qrefresh p1
 $ set +x
$

You can see  that now the  error message  was sent to  file "out" rather
than to standard error.

Slightly puzzled,
     Rainer

PS: Since I'm not subscribed  to the "mercurial-devel" list,  please try
hard to reply to both, the "mercurial-devel" list and yours truly :-)