Test 12 (testing urlhelper fails) is racy

[ffesti]

There is an empty line / new line moving around.

## ---------------------- ##
## 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)

Using sort as above doesn't fix it.

This has been mentioned in #3196 previously but deserves it's own ticket.

[pmatilai]

I just got

+++ /srv/rpmtests.dir/at-groups/12/stderr	2024-07-30 07:20:13.111240868 +0000
@@ -1,3 +1 @@
-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)

Bumping this to priority, this seems to come up far more often than some of the other racy tests we've had.