Tracking down a segfault in grep

  Thread 0 Crashed:: Dispatch queue: com.apple.main-thread
  0   libsystem_platform.dylib      	0x00007fffxxxxxxxx _platform_memchr$VARIANT$Haswell + 101
  1   libsystem_c.dylib             	0x00007fffxxxxxxxx __sfvwrite + 268
  2   libsystem_c.dylib             	0x00007fffxxxxxxxx fwrite + 142
  3   grep                          	0x00000001xxxxxxxx 0x10xxxxxxx + 13606
  4   grep                          	0x00000001xxxxxxxx 0x10xxxxxxx + 12465
  5   grep                          	0x00000001xxxxxxxx 0x10xxxxxxx + 8190
  6   libdyld.dylib                 	0x00007fffxxxxxxxx start + 1

  what /usr/bin/grep
    PROGRAM:grep  PROJECT:bsdgrep-17

  % echo i860 | grep --color -e i860 -e i86
  i860
  % uname -a
  Darwin xebulon.local 11.4.2 Darwin Kernel Version 11.4.2: Thu Aug 23 16:25:48 PDT 2012; root:xnu-1699.32.7~1/RELEASE_X86_64 x86_64
  % grep --version
  grep (GNU grep) 2.5.1
     ...
  % which grep
  /usr/bin/grep