if guix download unknown://some/where;
then false; else true; fi
-if guix download not/a/uri;
+if guix download /does-not-exist
then false; else true; fi
# This one should succeed.
guix download "file://$abs_top_srcdir/README"
+# And this one, without the URI scheme.
+guix download "$abs_top_srcdir/README"
+
# This one too, even if it cannot talk to the daemon.
output="t-download-$$"
trap 'rm -f "$output"' EXIT