I've managed to trace the error down to the use CGI qw(:cgi);
One of the unexpected side-effects of using CGI is that it invokes binmode() on STDIN, STDOUT, and STDERR. If somewhere upstream of the regex you assume "\n" instead of "\r\n", then something may be getting thrown off.

In reply to Re: Regex Unexplained Failure by dws
in thread Regex Unexplained Failure by Flame

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