[PATCH] Cygwin: spawn: Treat empty path as the current directory.

[Ken Brown]

On 6/27/2022 8:44 AM, Takashi Yano wrote:
> - With this patch, the empty path (empty element in PATH or PATH is
>    absent) is treated as the current directory as Linux does.
> Addresses: https://cygwin.com/pipermail/cygwin/2022-June/251730.html

It might be a good idea to include a comment in the code and the commit message 
that this feature is being added for Linux compatibility but that it is 
deprecated.  According to https://man7.org/linux/man-pages/man7/environ.7.html,

               As a legacy feature, a zero-length prefix (specified as
               two adjacent colons, or an initial or terminating colon)
               is interpreted to mean the current working directory.
               However, use of this feature is deprecated, and POSIX
               notes that a conforming application shall use an explicit
               pathname (e.g., .)  to specify the current working
               directory.

Alternatively, maybe this is a case where we should prefer POSIX compliance to 
Linux compatibility.  Corinna, WDYT?

Ken