Re: [PATCH] format-patch: cancel useAutoBase if base is invalid

[Junio C Hamano <gitster@pobox.com>]

Jacob Keller <jacob.e.keller@intel.com> writes:

> Make get_base_commit detect when useAutoBase is set, and avoid failing
> if the base commit is picked up automatically. We still attempt to fail
> if --base=auto is explicitly requested on the command line.

Makes sense.  I also think we should fail in such a broken base is
chosen, when useAutoBase is set by configuration and is not
overriden from the command line with an explicit use of --no-base
option, because the end-user expects an appropriate base to be used
that is computed automatically, but we are failing to find such a
base---going ahead silently in such a case would be wrong.

> Unfortunately, at least with how --base is handled by the option parsing
> now, if useAutoBase is true *and* --base=auto is provided, we'll still
> cancel the base option instead of failing.

If we are doing the usual "prime with configuration variables and
then override from the commnad line option" thing, then you cannot
tell these two cases apart, but I happen to think that it is better
to fail (and not to ignore silently) consistently whether the
"compute an appropriate base automatically" came from config or
command line, so...