fix mini_installer_sygyzy for msvs_cygwin_shell

BUG=123026
TBR=iannucci@chromium.org

Review URL: https://codereview.chromium.org/93693002

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@237662 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 237662