bug#30525: Unexpected matches for input data from a patch file

[Paul Eggert]

SF Markus Elfring wrote:
> I have tried the command “`printf -- '-\tif\n'|grep -E '^-\s+[^i]'`” out
> with the version “3.1-1.4”. I get no match which I expect in this use case.
>
> But I wonder why matches are displayed when if lines are passed from
> a patch file instead.

I assume it's because the if-lines match the regular expression in question, 
which is as it should be. If not, could you give a self-contained example 
illustrating the bug? Thanks.