Fix arc land for mercurial on windows

Summary:
arc for mercurial on windows was broken in several way.
Executing a command via passthru failed because passthru on windows
skips the shell so 'set HGPLAIN=1 & ...' was an invalid command. The
fix was to just not set HGPLAIN for passthru commands on windows.

Also removed hardcoded '' quotes in mercurial commands since windows
doesn't support single quots.

Test Plan: arc land --hold on a windows machine

Reviewers: epriestley

Reviewed By: epriestley

CC: Korvin, aran

Differential Revision: https://secure.phabricator.com/D6763
fix issue where multi-line dataproviders in phpunit were parsed incorrectly when displaying results

Summary: Found an issue where if arc unit runs phpunit and the datasets included a dataprovider which spanned multiple lines, it wasn't filtered out correctly in the result parser, this fixes it

Test Plan: accidentally ran tests against phpunit itself which exhibits this problem. no longer a problem after this fix, nothing else breaks.

Reviewers: epriestley

Reviewed By: epriestley

CC: aurelijus, epriestley, aran

Differential Revision: https://secure.phabricator.com/D6773