[RFC] test: Old shells and physical paths

Hi,

In working on a port, I have to tolerate an ancient shell.  The "cd"
and "pwd" commands don't understand the "-P" flag for physical paths,
as some tests use.  The biggest offender is "cd -P" causing a failure
in t/test-lib.sh (since 1bd9c64), which is sourced by every test
script.

This shell does understand the difference between physical and logical
paths, but the only way to choose which is with a shell option.  The
shell option is named "logical" which is not portable; GNU bash uses
the opposite, "physical".

Does anyone have any suggestions for how to handle this?

Would it be acceptable to instead force the platform's shell option
(if it exists) to always use physical paths for the tests and drop the
"-P" flags?

If not, is it worth maintaining compatibility wrappers for this one
obscure platform?

Thanks.

David