20120716-01:01:55 mengwong@cny2:~% perl -ple 's/(?<!a)b/a/g'
abb correctly becomes aba
abb
aba
But bbb wrongly becomes aaa.
bbb
aaa
Discuss.
20120716-01:02:17 mengwong@cny2:~% perl -v
This is perl 5, version 12, subversion 3 (v5.12.3) built for darwin-thread-multi-2level
(with 2 registered patches, see perl -V for more detail)
