From pcre changelog, version 6.7:

26. If a subpattern containing a named recursion or subroutine reference such
    as (?P>B) was quantified, for example (xxx(?P>B)){3}, the calculation of
    the space required for the compiled pattern went wrong and gave too small a
    value. Depending on the environment, this could lead to "Failed: internal
    error: code overflow at offset 49" or "glibc detected double free or
    corruption" errors.

Acknowledgements:

Red Hat would like to thank Ludwig Nussel for reporting this issue.