tests: dis/allow '.' in PATH?

[Bernhard Voelker]

GNU findutils got a bug report for a failing test in the testsuite [1].
It turned out that the calling environment had the current directory '.'
in PATH.  This triggered a warning in `find -execdir ...` and therefore
made some tests fail.

[1] https://lists.gnu.org/r/bug-findutils/2021-11/msg00004.html

Of course, the findutils tests could (and probably will) remove '.' from PATH,
but I wonder if this should or should not be done for other packages via a 
change
in 'tests/init.sh' as well?
If a certain test needs '.' in the PATH, it will have to add it anyway.

Any comments?

Have a nice day,
Berny