general protection faults with "git grep" version 1.7.7.1

[Markus Trippelsdorf <markus@trippelsdorf.de>]

Suddenly I'm getting strange protection faults when I run "git grep" on
the gcc tree:

git[4245] general protection ip:7f291f01461f sp:7fff5618a8b0 error:0 in libc-2.14.90.so[7f291ef9a000+15d000]

 % gdb git
GNU gdb (Gentoo 7.3.1 p1) 7.3.1
Copyright (C) 2011 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-pc-linux-gnu".
For bug reporting instructions, please see:
<http://bugs.gentoo.org/>...
Reading symbols from /usr/bin/git...done.
(gdb) run grep composite_pointer_type
Starting program: /usr/bin/git grep composite_pointer_type
warning: no loadable sections found in added symbol-file system-supplied DSO at 0x7ffff7ffa000
[Thread debugging using libthread_db enabled]
[New Thread 0x7ffff7859700 (LWP 18367)]
[New Thread 0x7ffff7058700 (LWP 18368)]
[New Thread 0x7ffff6857700 (LWP 18369)]
[New Thread 0x7ffff6056700 (LWP 18370)]
[New Thread 0x7ffff5855700 (LWP 18371)]
[New Thread 0x7ffff5054700 (LWP 18372)]
[New Thread 0x7ffff4853700 (LWP 18373)]
[New Thread 0x7ffff4052700 (LWP 18374)]

Program received signal SIGSEGV, Segmentation fault.
_int_malloc (av=0x7ffff7bbb600, bytes=21) at malloc.c:3463
3463        while ((pp = catomic_compare_and_exchange_val_acq (fb, victim->fd, victim))
(gdb) bt
#0  _int_malloc (av=0x7ffff7bbb600, bytes=21) at malloc.c:3463
#1  0x00007ffff78d7300 in __GI___libc_malloc (bytes=21) at malloc.c:2924
#2  0x00007ffff78dc692 in __GI___strdup (s=0x7ffff2665760 "gcc/ada/i-cexten.ads") at strdup.c:43
#3  0x00000000004d5069 in xstrdup (str=0x7ffff2665760 "gcc/ada/i-cexten.ads") at wrapper.c:23
#4  0x000000000042c448 in grep_file_async (filename=0x7ffff2665760 "gcc/ada/i-cexten.ads", name=0x59fee0 "gcc/ada/i-cexten.ads", 
    opt=<optimized out>) at builtin/grep.c:148
#5  grep_file (opt=0x7fffffffbfc0, filename=0x7ffff2665760 "gcc/ada/i-cexten.ads") at builtin/grep.c:459
#6  0x000000000042ddb0 in grep_cache (cached=0, pathspec=0x7fffffffbf70, opt=0x7fffffffbfc0) at builtin/grep.c:528
#7  cmd_grep (argc=<optimized out>, argv=0x7ffff2665760, prefix=0x0) at builtin/grep.c:1062
#8  0x00000000004045b0 in run_builtin (argv=0x7fffffffe110, argc=2, p=0x536ba0) at git.c:308
#9  handle_internal_command (argc=2, argv=0x7fffffffe110) at git.c:466
#10 0x00000000004047ac in run_argv (argv=0x7fffffffdfa0, argcp=0x7fffffffdfac) at git.c:512
#11 main (argc=2, argv=0x7fffffffe110) at git.c:585
(gdb) 

or:

 % git grep composite_pointer_type
*** glibc detected *** git: double free or corruption (fasttop): 0x0000000001919800 ***
======= Backtrace: =========
/lib64/libc.so.6(+0x792b6)[0x7f6ad1d392b6]
git[0x42bebb]
/lib64/libpthread.so.0(+0x7c9e)[0x7f6ad202ec9e]
/lib64/libc.so.6(clone+0x6d)[0x7f6ad1d99b8d]
======= Memory map: ========
00400000-00536000 r-xp 00000000 08:12 2310166                            /usr/bin/git
00536000-0053d000 rw-p 00136000 08:12 2310166                            /usr/bin/git
0053d000-0058b000 rw-p 00000000 00:00 0
01906000-01927000 rw-p 00000000 00:00 0                                  [heap]
...

And strange output:
...
gcc/cp/typeck.c:        result_type = composite_pointer_type (type0, type1, op0, op1,
gcc/cp/typeck.c:        result_type = composite_pointer_type (type0, type1, op0, op1,
error: 'gcc/testsuite/ada/acats/tests/c5/c54a24a.ada': short read No such file or directory
error: 'gcc/testsuite/ada/acats/tests/c5/c54a13a.ada': short read No such file or directory
error: 'gcc/testsuite/ada/acats/tests/c6/c64104m.ada': short read No such file or directory
error: 'gcc/testsuite/ada/acats/tests/cd/cd7101f.dep': short read No such file or directory
error: 'gcc/testsuite/ada/acats/tests/ce/ce3904a.ada': short read No such file or directory
error: 'gcc/testsuite/g++.dg/abi/pr39188-3b.C': short read No such file or directory
error: '<90>Dz^A': short read Is a directory

Note that all the above files actually exist.
All of this started with version v1.7.7.1, which I installed today. I
never had any problems with git before.
Any ideas what might be going on?
-- 
Markus