RFE: Split diff.noprefix for git-diff and git-format-patch (was: http-backend: give a hint that web browser access is not supported)

[Jan Engelhardt <jengelh@inai.de>]

On Thursday 2021-12-02 08:38, Junio C Hamano wrote:
>
>>  http-backend.c          | 36 +++++++++++++++++++++++++++-----
>>  t/t5561-http-backend.sh | 46 ++++++++++++++++++++---------------------
>>  2 files changed, 54 insertions(+), 28 deletions(-)
>>
>> diff --git http-backend.c http-backend.c
>> index 3d6e2ff17f..f7858e9c49 100644
>> --- http-backend.c
>> +++ http-backend.c
>
>Please fix your format-patch settings.  The comparisons should be
>between a/http-backend.c and b/http-backend.c and not between the
>same path at the top-level.

You are right. But..

In interactive git-diff invocations, prefixless is the arguably desired mode,
so as to facilitate xterm copy-and-paste of the pathname (since a/ does not
exist, you would want to have it in the copypaste operation anywhere).

I can see why git-format-patch would make use of the "diff.noprefix"
config directive, but equally, it's a bug that diff.noprefix has such
broad implications and that there is no way to distinguish between
diff and format-patch.