bug#65156: 29.1; Reading from pipe with --insert or insert-file-contents no longer supported

[Paul Eggert]

On 2023-08-08 12:27, Eli Zaretskii wrote:
> Paul, can there be a regular file that is not seekable?

No.

The current code on master is a bit of a mess. There's nothing wrong 
with using a positive BEG on a seekable and non-regular file, for 
example; the old doc string was wrong and now the code has been changed 
to match the doc string unfortunately. Nor is there anything wrong if 
BEG is 0 on a non-seekable file (though this latter issue is 
longstanding and so I guess nobody cares).

There are surely some gotchas involving the REPLACE arg of 
insert-file-contents too, but it's hard to tell because the doc string 
seems to be corrupted for the case where REPLACE is 'if-regular' and I 
don't know what it's trying to say.