As reported in StackOverflow (http://stackoverflow.com/questions/23004527) (with a wrong expectation), the following regex pattern with the
* operator does not match.
"ab" =~ /(?!^a).*b/ # => nil
? is used instead, it seems to match correctly:
"ab" =~ /(?!^a).?b/ # => 1
According to the original reporter of the linked site, this does not happen in Ruby 1.9.3.