Sort output for test case to avoid race condition

[ffesti]

Solves #3106

We should probably understand why the urlhelper tests are racy before merging.

[ffesti]

OK, here it is, looks like there is an empty line moving around. And even worse the sort doesn't seem to catch it...

## ---------------------- ##
## Detailed failed tests. ##
## ---------------------- ##

#                             -*- compilation -*-
12. rpmgeneral.at:401: testing urlhelper fails ...
/rpmgeneral.at:404:
runroot rpm --define "_urlhelper /bin/false" --root /srv/test -qp https://example.com/foo-0.1-1.noarch.rpm 2> >(sed 's| /.*rpm-tmp.* https| rpm-tmp https|' | sort >&2)

--- -	2024-07-05 11:50:09.240892131 +0000
+++ /srv/rpmtests.dir/at-groups/12/stderr	2024-07-05 11:50:09.238121757 +0000
@@ -1,3 +1,3 @@
+
 error: Executing url helper "/bin/false rpm-tmp https://example.com/foo-0.1-1.noarch.rpm" failed with status 1
 error: open of https://example.com/foo-0.1-1.noarch.rpm failed: No such file or directory
-
12. rpmgeneral.at:401: 12. urlhelper fails (rpmgeneral.at:401): FAILED (rpmgeneral.at:404)

[ffesti]

Ok, I dropped the patch for the url helper test. Let's just fix this and worry about that one later.

[dmnks]

Nice! Thanks.