systemd-run would fail when run with -M or -H and an absolute path,
if this path did not exists locally. Allow it to continue, since we
don't have a nice way of checking if the binary exists remotely.
The case where -M or -H is used and a local path is unchanged, and we
still iterate over $PATH to find the binary. We need to convert to an
absolute path, and we don't have a nice mechanism to check remotely,
so we assume that the binary will be located in the same place locally
and remotely.
http://lists.freedesktop.org/archives/systemd-devel/2014-November/025418.html
Otherwise they get optimized out when CPPFLAGS='-DNDEBUG' is used, and that
causes the tests to fail.
Tested:
- make check TESTS='test-path-util' CPPFLAGS='-DNDEBUG'
In contrast to a filename-only argument, find_binary() did not
actually check if an path exists, allowing the code to fail later on.
This was OK, but it seems nicer to treat both paths identically.
Also take advantage of path_make_absolute_cwd doing strdup() by itself
if necessary to simplify.
The only problem is that libgen.h #defines basename to point to it's
own broken implementation instead of the GNU one. This can be fixed
by #undefining basename.
