[Monotone-devel] Bogus merge with 0.38

[Julio M. Merino Vidal]

Hello,

I was doing a change to a workspace when I realized that I could  
better split it in two different commits.  So I checked out a fresh  
revision of the single-head I had, made part of the change and  
committed it.

Then I went back to the former repository, which already had the  
whole changes applied (the part I already committed and the rest) and  
did an update.  I expected some conflicts might arise, but not what  
happened.

First, look at the following messages printed by mtn (0.38 release  
under OS X 10.4.11):

----- cut here -----
calypso:~/Projects/atf/src> mtn update
mtn: updating along branch 'org.NetBSD.atf.src'
mtn: selected update target 6c776507a34b435d02334f1771a99c365c5841a3
mtn: warning: Content changes to the file "subrs/atf.config.subr.in"
mtn: warning: will be ignored during this merge as the file has been
mtn: warning: removed on one side of the merge.  Affected revisions  
include:
mtn: warning: Revision : 0000000000000000000000000000000000000004
mtn: modifying configure.ac
mtn: updated to base revision 6c776507a34b435d02334f1771a99c365c5841a3
calypso:~/Projects/atf/src>
----- cut here -----

That revision number of '0000...0004' looks bogus.

But then, the wrong part.  mtn diff on configure.ac, after the merge,  
shows that something really weird went on:

----- cut here -----
calypso:~/Projects/atf/src> mtn diff configure.ac
#
# old_revision [6c776507a34b435d02334f1771a99c365c5841a3]
#
# patch "configure.ac"
#  from [14873357f8f3bd2164bd8d0bda85362c6eef4c0a]
#    to [685477d2c6d738d23377de1f271ee6f112c473d4]
#
============================================================
--- configure.ac        14873357f8f3bd2164bd8d0bda85362c6eef4c0a
+++ configure.ac        685477d2c6d738d23377de1f271ee6f112c473d4
@@ -172,8 +172,6 @@ if test x"${ATF_SHELL}" = x""; then
 fi
 if test x"${ATF_SHELL}" = x""; then
     AC_MSG_ERROR([No POSIX shell interpreter found; maybe set  
ATF_SHELL?])
-fi
-
 dnl  
-----------------------------------------------------------------------
 dnl Check for required tools.
 dnl  
-----------------------------------------------------------------------
@@ -184,7 +182,7 @@ dnl ------------------------------------
 dnl Finally, generate output.
 dnl  
-----------------------------------------------------------------------

-AC_OUTPUT([Makefile subrs/atf.config.subr])
+AC_OUTPUT([Makefile])

 if test ${enable_shared} = yes; then
     AC_MSG_WARN([Shared libraries with unstable ABIs/APIs have been  
enabled.])
calypso:~/Projects/atf/src>
----- cut here -----

The first chunk is completely bogus.

This is what the head of the repository did on that file:

----- cut here -----
#
# patch "configure.ac"
#  from [40b0b76d69c39ea507c4c7e562658d8f47ab7e54]
#    to [14873357f8f3bd2164bd8d0bda85362c6eef4c0a]
#
============================================================
--- configure.ac        40b0b76d69c39ea507c4c7e562658d8f47ab7e54
+++ configure.ac        14873357f8f3bd2164bd8d0bda85362c6eef4c0a
@@ -174,16 +174,6 @@ fi
     AC_MSG_ERROR([No POSIX shell interpreter found; maybe set  
ATF_SHELL?])
 fi

-AC_MSG_CHECKING([whether ${ATF_SHELL} supports trap -])
-output=`${ATF_SHELL} -c 'trap -- -' 2>&1`
-if test x"${output}" != x""; then
-    AC_SUBST([SH_TRAP_DASH], [no])
-    AC_MSG_RESULT([no])
-else
-    AC_SUBST([SH_TRAP_DASH], [yes])
-    AC_MSG_RESULT([yes])
-fi
-
 dnl  
-----------------------------------------------------------------------
 dnl Check for required tools.
 dnl  
-----------------------------------------------------------------------
----- cut here -----

And this is the diff of the file in the final workspace *before* the  
merge.  As you can see, mtn confused part of the first chunk here and  
killed some code before it in the results:

----- cut here -----
--- configure.ac        40b0b76d69c39ea507c4c7e562658d8f47ab7e54
+++ configure.ac        ede58dacfc56401317b4637f3afda44b0757c2e7
@@ -174,16 +174,6 @@ fi
     AC_MSG_ERROR([No POSIX shell interpreter found; maybe set  
ATF_SHELL?])
 fi

-AC_MSG_CHECKING([whether ${ATF_SHELL} supports trap -])
-output=`${ATF_SHELL} -c 'trap -- -' 2>&1`
-if test x"${output}" != x""; then
-    AC_SUBST([SH_TRAP_DASH], [no])
-    AC_MSG_RESULT([no])
-else
-    AC_SUBST([SH_TRAP_DASH], [yes])
-    AC_MSG_RESULT([yes])
-fi
-
 dnl  
-----------------------------------------------------------------------
 dnl Check for required tools.
 dnl  
-----------------------------------------------------------------------
@@ -194,7 +184,7 @@ dnl ------------------------------------
 dnl Finally, generate output.
 dnl  
-----------------------------------------------------------------------

-AC_OUTPUT([Makefile subrs/atf.config.subr])
+AC_OUTPUT([Makefile])

 if test ${enable_shared} = yes; then
     AC_MSG_WARN([Shared libraries with unstable ABIs/APIs have been  
enabled.])
----- cut here -----

Is this a known bug?  Has it already been fixed?

If you need more details to diagnose this, please let me know.  The  
database is public, by the way.

Thank you.