Merge branch 'tz/cred-netrc-cleanup'

Build and test procedure for netrc credential helper (in contrib/) has been updated. * tz/cred-netrc-cleanup: git-credential-netrc: make "all" default target of Makefile git-credential-netrc: fix exit status when tests fail git-credential-netrc: use in-tree Git.pm for tests git-credential-netrc: minor whitespace cleanup in test script