grep crashed with SIGABRT in __assert_fail_base()

Was running

    grep -Er -e '^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\9\8\7\6\5\4\3\2\1$' .

in /usr/share/dict.

ProblemType: Crash
DistroRelease: Ubuntu 12.04
Package: grep 2.10-1 [modified: bin/egrep bin/fgrep bin/grep]
ProcVersionSignature: Ubuntu 3.2.0-23.36-generic 3.2.14
Uname: Linux 3.2.0-23-generic x86_64
ApportVersion: 2.0.1-0ubuntu1
Architecture: amd64
Date: Wed Apr 11 12:44:32 2012
ExecutablePath: /bin/grep
InstallationMedia: Ubuntu 11.10 "Oneiric Ocelot" - Release amd64 (20111011)
ProcCmdline: grep --color=auto -r -E ^(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?)(.?).?\\9\\8\\7\\6\\5\\4\\3\\2\\1$ .
ProcEnviron:
 SHELL=/bin/bash
 TERM=xterm
 PATH=(custom, user)
 LANG=en_GB.UTF-8
 LANGUAGE=en_GB
Signal: 6
SourcePackage: grep
StacktraceTop:
 raise () from /lib/x86_64-linux-gnu/libc.so.6
 abort () from /lib/x86_64-linux-gnu/libc.so.6
 ?? () from /lib/x86_64-linux-gnu/libc.so.6
 __assert_fail () from /lib/x86_64-linux-gnu/libc.so.6
 ?? () from /lib/x86_64-linux-gnu/libc.so.6
Title: grep crashed with SIGABRT in raise()
UpgradeStatus: Upgraded to precise on 2012-03-09 (32 days ago)
UserGroups: adm cdrom dialout lpadmin plugdev sambashare sudo www-data