Re: [PATCH v3 4/5] Add `human` format to test-tool

"Stephen P. Smith" [off-list ref] writes:

Add the human format support to the test tool so that TEST_DATE_NOW
can be used to specify the current time.

This sounds sensible, but let's do s/TEST_DATE_NOW/GIT_&/ to make
sure that we will not pick up somebody else's random environment
variable in production Git binary.  

The name of the original environment variable was OK as it was very
much limited to t/helper/test-date.c, but a name that we'll pay
attention to in production binary is a different matter.

All calls to gettimeofday() were replaced by calls to get_time().

Yup, good.

The next to go would be the getenv(TEST_DATE_NOW) at the beginning
of cmd__date(), which probably would lead to simplification to
functions it calls by losing &now parameter.  But that is a separate
clean-up.