From 117c3c56ee7ab70b165bdfe27bdaf84a15d0a2e9 Mon Sep 17 00:00:00 2001
From: Joe Stringer <joe@cilium.io>
Date: Thu, 15 Jul 2021 16:03:27 -0700
Subject: [PATCH] backporting: Detect only one related commit

[ upstream commit 9abbbbfef0431f0e54dbe863648329c7bf138ee4 ]

Recently, the check-stable script has suggested every single possible
match for commits where the name does not uniquely identify the commit.
This can be a bit confusing to backporters since it looks like there are
many commits to backport as part of this PR, but the second and later
ones are not necessary to backport.

 * PR: 16589 -- vagrant: Bump all Vagrant box versions (@pchaigno) -- https://github.com/cilium/cilium/pull/16589
   Merge with 1 commit(s) merged at: Tue, 22 Jun 2021 12:36:17 -0700!
     Branch:     master (!)                          refs/pull/16589/head
                 ----------                          -------------------
     v (start)
     |  edf76fb1ef6b58d5ef90b439d54134f314ed086e
5bef5d77137a9ecc5d3f2b72149307ffdd52cd42
4dc60e6faf654d7424ee959867a774205b3fed13
816b3231cdbc39f4bcdd3e6f5b40a056459a478c
51826b31087496d108044f3bffbf304580fffb4a
df8238d451d755d5be75e202be89b4f88067c77b
a4e7bc6c1f0e96078793458b6719b9a3999b89db via fb723f8133c40faa068a5a401f594622668b2753 ("vagrant: Bump all Vagrant box versions")
     v (end)

Probably within the last year of commits, we should be able to correlate
the exact commit that needs backporting, so iterate through those to
find the exact commit. If none of those are the correct commit, fail out
and push back to the backporter to figure out.

This allows us to now accurately pick the correct commit in most cases:

 * PR: 16589 -- vagrant: Bump all Vagrant box versions (@pchaigno) -- https://github.com/cilium/cilium/pull/16589
   Merge with 1 commit(s) merged at: Tue, 22 Jun 2021 12:36:17 -0700!
     Branch:     master (!)                          refs/pull/16589/head
                 ----------                          -------------------
     v (start)
     |  edf76fb1ef6b58d5ef90b439d54134f314ed086e via fb723f8133c40faa068a5a401f594622668b2753 ("vagrant: Bump all Vagrant box versions")
     v (end)

Manually tested by substituting a known commit into 'related_commits',
and by checking the current v1.8 backports which includes an ambiguous
commit due to a revert+reapply in the master branch.

Signed-off-by: Joe Stringer <joe@cilium.io>
Signed-off-by: Paul Chaignon <paul@cilium.io>
---
 contrib/backporting/check-stable | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/contrib/backporting/check-stable b/contrib/backporting/check-stable
index 198a2d88b957..475a569f3bd9 100755
--- a/contrib/backporting/check-stable
+++ b/contrib/backporting/check-stable
@@ -156,11 +156,17 @@ generate_commit_list_for_pr () {
     entry_sha=${entry_array[1]}
     entry_sub=${entry_array[@]:2}
     entry_sub_re="^$(sed 's/[.^$*+?()[{\|]/\\&/g' <<< "$entry_sub")$" # adds backslashes for extended regex
-    upstream_commit="$(git log --since="1year" --pretty="%H" --no-merges --extended-regexp --grep "$entry_sub_re" $REMOTE/master)"
-    upstream_id="$(git log -n1 --pretty=format:"%ae%at" $upstream_commit)"
-    if [ "$entry_id" == "${upstream_id}" ]; then
-      echo -e "     |  ${upstream_commit} via $entry_sha (\"$entry_sub\")"
-    else
+    related_commits="$(git log --since="1year" --pretty="%H" --no-merges --extended-regexp --grep "$entry_sub_re" $REMOTE/master)"
+    found_commit=0
+    for upstream_commit in ${related_commits}; do
+      upstream_id="$(git log -n1 --pretty=format:"%ae%at" $upstream_commit)"
+      if [ "$entry_id" == "${upstream_id}" ]; then
+        echo -e "     |  ${upstream_commit} via $entry_sha (\"$entry_sub\")"
+        found_commit=1
+        break
+      fi
+    done
+    if [ "$found_commit" -ne 1 ]; then
       echo -e "     |  Warning: No commit correlation found!    via $entry_sha (\"$entry_sub\")"
     fi
   done < $tmp_file