Re: master a89c86888c4 1/3: Detect developer builds in git worktrees as well

[Po Lu]

Björn Bidar <bjorn.bidar@thaodan.de> writes:

> The reference to the autoconf manual makes me wonder what would be the
> cutoff point for older systems to support. Some of these systems are
> quite ancient.

Autoconf scripts should abide by each guideline within the Autoconf
manual irrespective of which systems they elect to support, for there is
always the possibility that a new system may emerge evincing bugs
comparable to those manifested by earlier ones, or that someone might
wish to transplant Emacs onto an older system; whereupon the configure
script ought to serve as assistance, not as an impediment.

In this particular case, all Unix systems (back to Version 7 Unix)
support `test -o'.  Non-XSI POSIX shells might not, and such shells do
exist or may exist in the future.  Moreover, `test -o' suffers from
inherent ambiguities that render it unreliable under circumstances that
are difficult to detect, so it is better to forestall such errors by
eschewing `test -o' uniformly.