format-patch crashes with a huge patchset

["Michael S. Tsirkin" <mst@redhat.com>]

I tried to fump the whole history of qemu with format-patch.
It crashes both with v2.0.0-rc2-21-g6087111
and with git 1.8.3.1:

~/opt/libexec/git-core/git-format-patch --follow -o patches/all
e63c3dc74bfb90e4522d075d0d5a7600c5145745..

Backtrace:


Program received signal SIGSEGV, Segmentation fault.
0x0814d9d5 in try_to_follow_renames (opt=0xffffc8e4,
base=base@entry=0x816e4fe "", t2=0xffffbdf0, t1=0xffffbddc) at
tree-diff.c:227
227             diff_opts.single_follow = opt->pathspec.items[0].match;
Missing separate debuginfos, use: debuginfo-install
openssl-libs-1.0.1e-37.fc19.1.i686
(gdb) p opt
$1 = (struct diff_options *) 0xffffc8e4
(gdb) where
#0  0x0814d9d5 in try_to_follow_renames (opt=0xffffc8e4,
base=base@entry=0x816e4fe "", t2=0xffffbdf0, t1=0xffffbddc) at
tree-diff.c:227
#1  diff_tree_sha1 (old=0x97469b4
"\372\022\366\336k\345\236\362\062K\021\236\300\227\036\302\217\251\202f", 
    new=new@entry=0x9746994 "$\305H\250)\237\203\266ya\311W\n\274
\n\027^*\221", base=base@entry=0x816e4fe "", opt=opt@entry=0xffffc8e4)
    at tree-diff.c:305
#2  0x080fb83d in log_tree_diff (log=0xffffbf28, commit=0x9734730,
opt=0xffffc618) at log-tree.c:780
#3  log_tree_commit (opt=opt@entry=0xffffc618,
commit=commit@entry=0x9734730) at log-tree.c:810
#4  0x08088406 in cmd_format_patch (argc=<optimized out>,
argv=0xffffccc4, prefix=0x0) at builtin/log.c:1510
#5  0x0804c666 in run_builtin (argv=0xffffccc4, argc=5, p=0x81cb524
<commands+420>) at git.c:314
#6  handle_builtin (argc=5, argv=0xffffccc4) at git.c:487
#7  0x0804bc22 in main (argc=5, av=0xffffccc4) at git.c:584
(gdb) p opt->pathspec.items
$2 = (struct pathspec_item *) 0x0


Did not debug further: could be related to the fact
swap is disabled on my box, so attempts to allocate
huge amounts of RAM might fail.

Still should not segv I think ...

-- 
MST