[tests/selinux] pr775-checkpolicy-revdeps: test-pr: Simplify the test list command

[tests/selinux] pr775-checkpolicy-revdeps: test-pr: Simplify the test list command

[Ondrej Mosnacek]

            A new commit has been pushed.

            Repo   : tests/selinux
            Branch : pr775-checkpolicy-revdeps
            Commit : d8af40901534ee2bebf26c290423defff6266eca
            Author : Ondrej Mosnacek <omosnace@redhat.com>
            Date   : 2020-07-27T16:55:20+02:00
            Stats  : +1/-2 in 1 file(s)
            URL    : https://src.fedoraproject.org/tests/selinux/c/d8af40901534ee2bebf26c290423defff6266eca?branch=pr775-checkpolicy-revdeps

            Log:
            test-pr: Simplify the test list command

* Use `git diff` instead of `git log` and avoid computing the number of
  commits.
* Drop the redundant `grep '/'` and `tr ' ' '\n'` from the pipeline.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>

---
diff --git a/tests-pr.yml b/tests-pr.yml
index 2a4c2a2..7d04192 100644
--- a/tests-pr.yml
+++ b/tests-pr.yml
@@ -5,8 +5,7 @@
   pre_tasks:
     - name: Generate list of tests in this PR
       shell: |
-          COMMIT_NUM=$(git cherry origin/master | wc -l)
-          git log --format= --stat --name-only HEAD -$COMMIT_NUM | grep '/' | sed '/\//!d;s#\(.*\)/.*#\1#' | sort -u | tr '\n' ' ' | xargs
+          git diff --stat --name-only origin/master HEAD | sed '/\//!d;s#\(.*\)/.*#\1#' | sort -u | xargs
       delegate_to: localhost
       register: tests_list