Partial revert "Do not report warning when git shows new reference (go-gitea#6540)"

This reverts commit af5d96e.

Except for the test case because

Fix mirror bug (go-gitea#33224)

implements it now.

Author: earl-warren

services/mirror/mirror_pull.go

@@ -187,7 +187,6 @@ func parseRemoteUpdateOutput(output, remoteName string) []*mirrorSyncResult {
 				newCommitID: shas[1],
 			})
 
-		case strings.HasPrefix(lines[i], " * [new ref]"): // new reference - nothing to do
 		default:
 			log.Warn("parseRemoteUpdateOutput: unexpected update line %q", lines[i])
 		}

services/mirror/mirror_test.go

@@ -21,7 +21,7 @@ func Test_parseRemoteUpdateOutput(t *testing.T) {
  * [new ref]         refs/pull/516/head  -> refs/pull/516/head
  `
 	results := parseRemoteUpdateOutput(output, "origin")
-	assert.Len(t, results, 6)
+	assert.Len(t, results, 8)
 	assert.EqualValues(t, "refs/tags/v0.1.8", results[0].refName.String())
 	assert.EqualValues(t, gitShortEmptySha, results[0].oldCommitID)
 	assert.EqualValues(t, "", results[0].newCommitID)
@@ -45,4 +45,12 @@ func Test_parseRemoteUpdateOutput(t *testing.T) {
 	assert.EqualValues(t, "refs/heads/test3", results[5].refName.String())
 	assert.EqualValues(t, "957a993", results[5].oldCommitID)
 	assert.EqualValues(t, "a87ba5f", results[5].newCommitID)
+
+	assert.EqualValues(t, "refs/pull/27/merge", results[6].refName.String())
+	assert.EqualValues(t, gitShortEmptySha, results[6].oldCommitID)
+	assert.EqualValues(t, "", results[6].newCommitID)
+
+	assert.EqualValues(t, "refs/pull/516/head", results[7].refName.String())
+	assert.EqualValues(t, gitShortEmptySha, results[7].oldCommitID)
+	assert.EqualValues(t, "", results[7].newCommitID)
 }