Git in next is broken

From: Nicolas Pitre <nico@fluxnic.net>
Date: Nov 12, 2009, 20:36 UTC
Message-ID: <alpine.LFD.2.00.0911121513470.16711@xanadu.home>

Simply issuing a "git fetch" in my copy of git.git makes glibc complain with this:

*** glibc detected *** git: corrupted double-linked list: 0x0000000000974180 ***

The gdb backtrace is:

(gdb) bt
#0  0x0000003c76632f05 in raise () from /lib64/libc.so.6
#1  0x0000003c76634a73 in abort () from /lib64/libc.so.6
#2  0x0000003c76672438 in __libc_message () from /lib64/libc.so.6
#3  0x0000003c76677ec8 in malloc_printerr () from /lib64/libc.so.6
#4  0x0000003c7667a23e in _int_free () from /lib64/libc.so.6
#5  0x0000003c7667a486 in free () from /lib64/libc.so.6
#6  0x0000000000493f3f in ref_remove_duplicates (ref_map=0x7562b0)
    at remote.c:756
#7  0x0000000000424afc in get_ref_map () at builtin-fetch.c:165
#8  do_fetch () at builtin-fetch.c:644
#9  cmd_fetch (argc=<value optimized out>, argv=0x7fffffffe6a0,
    prefix=<value optimized out>) at builtin-fetch.c:754
#10 0x0000000000403d83 in run_builtin () at git.c:251
#11 handle_internal_command (argc=1, argv=0x7fffffffe6a0) at git.c:396
#12 0x0000000000403f2d in run_argv () at git.c:438
#13 main (argc=1, argv=0x7fffffffe6a0) at git.c:509

Bisection reveals the following culprit:

commit 73cf0822b2a4ffa7ad559d1f0772e39718fc7776
Author: Julian Phillips <julian@quantumfyre.co.uk>
Date:   Sun Oct 25 21:28:11 2009 +0000

    remote: Make ref_remove_duplicates faster for large numbers of refs

    The ref_remove_duplicates function was very slow at dealing with very
    large numbers of refs.  This is because it was using a linear search
    through all remaining refs to find any duplicates of the current ref.

    Rewriting it to use a string list to keep track of which refs have
    already been seen and removing duplicates when they are found is much
    more efficient.

    Signed-off-by: Julian Phillips <julian@quantumfyre.co.uk>
    Signed-off-by: Junio C Hamano <gitster@pobox.com>

Reverting that commit from next does indeed fix the problem. Note that this problem doesn't show up with all repositoryes.

Nicolas