Fix typo with regex_match_to_long

Sponsored-by: EMC / Isilon Storage Division
Merge pull request #95 from yaneurabeya/fix-tap_helper-regex_match_too_long-typo

Fix typo with regex_match_to_long
Merge branch 'master' into plug-leaks-with-regex-handling
Copy original_preg and fix a double-free

- Make a copy of original_preg so the regular expression object is valid
when the error is constructed [*].
- Fix a double-free with preg in kyua_tap_try_parse_plan(..) (I fixed this
before on a different branch..).

[*] Submitted-by: jmmv
Sponsored-by: EMC / Isilon Storage Division