fixup! git stash: make sure that .git/logs/refs/ exists
t7102: do not assume the system encoding is utf-8

The commit_msg function has an assumption that the string is being output
as utf-8. On Windows this is not true so always convert from the system
encoding to the desired encoding.

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>
t6006: be explicit about the encoding of test strings for msysgit

Signed-off-by: Pat Thoyts <patthoyts@users.sourceforge.net>