Fix Default Branch issue on GitOps Comment Event in Github

Issue: when a user uses GitOps comment on pushed commit in
Github, Head and Base branch is set as `main` in hardcoded string
and considered default branch here but default could differ by repos
like it could be `master` or `trunk` as well.

Fix: use Event.Repository.DefaultBranch field for Head and Base
branch value in this case.

Signed-off-by: Zaki Shaikh <[email protected]>

Author: zakisk

pkg/provider/github/parse_payload.go

@@ -429,8 +429,9 @@ func (v *Provider) handleCommitCommentEvent(ctx context.Context, event *github.C
 	runevent.TriggerTarget = triggertype.Push
 	opscomments.SetEventTypeAndTargetPR(runevent, event.GetComment().GetBody())
 
-	// Set main as default branch to runevent.HeadBranch, runevent.BaseBranch
-	runevent.HeadBranch, runevent.BaseBranch = "main", "main"
+	defaultBranch := event.GetRepo().GetDefaultBranch()
+	// Set Event.Repository.DefaultBranch as default branch to runevent.HeadBranch, runevent.BaseBranch
+	runevent.HeadBranch, runevent.BaseBranch = defaultBranch, defaultBranch
 	var (
 		branchName string
 		prName     string

pkg/provider/github/parse_payload_test.go

@@ -48,7 +48,7 @@ var sampleRepo = &github.Repository{
 		Login: github.Ptr("owner"),
 	},
 	Name:          github.Ptr("reponame"),
-	DefaultBranch: github.Ptr("defaultbranch"),
+	DefaultBranch: github.Ptr("main"),
 	HTMLURL:       github.Ptr("https://github.com/owner/repo"),
 }