chore(cleanup): GitRepo.GetCommit is equivalent to GitRepo.IsBranchExist

Since go-git was dropped in a21128a734,
IsBranchExist relies on git-cat-file to figure out if a commit ID
exists.

There is no need to fallback to GetCommit if IsBranchExist determines
the commit does not exist and it will come to the same conclusion.

routers/api/v1/repo/pull.go

@@ -1116,13 +1116,8 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 	baseIsBranch := ctx.Repo.GitRepo.IsBranchExist(baseBranch)
 	baseIsTag := ctx.Repo.GitRepo.IsTagExist(baseBranch)
 	if !baseIsCommit && !baseIsBranch && !baseIsTag {
-		// Check for short SHA usage
+		ctx.NotFound("BaseNotExist")
-		if baseCommit, _ := ctx.Repo.GitRepo.GetCommit(baseBranch); baseCommit != nil {
+		return nil, nil, nil, "", ""
-			baseBranch = baseCommit.ID.String()
-		} else {
-			ctx.NotFound("BaseNotExist")
-			return nil, nil, nil, "", ""
-		}
 	}
 
 	headRepo := repo_model.GetForkedRepo(ctx, headUser.ID, baseRepo.ID)
@@ -1203,14 +1198,8 @@ func parseCompareInfo(ctx *context.APIContext, form api.CreatePullRequestOption)
 	headIsBranch := headGitRepo.IsBranchExist(headBranch)
 	headIsTag := headGitRepo.IsTagExist(headBranch)
 	if !headIsCommit && !headIsBranch && !headIsTag {
-		// Check if headBranch is short sha commit hash
+		ctx.NotFound("IsRefExist", nil)
-		if headCommit, _ := headGitRepo.GetCommit(headBranch); headCommit != nil {
+		return nil, nil, nil, "", ""
-			headBranch = headCommit.ID.String()
-		} else {
-			headGitRepo.Close()
-			ctx.NotFound("IsRefExist", nil)
-			return nil, nil, nil, "", ""
-		}
 	}
 
 	headBranchRef := headBranch

routers/web/repo/compare.go

@@ -312,22 +312,16 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 	baseIsTag := ctx.Repo.GitRepo.IsTagExist(ci.BaseBranch)
 
 	if !baseIsCommit && !baseIsBranch && !baseIsTag {
-		// Check if baseBranch is short sha commit hash
+		if ci.BaseBranch == ctx.Repo.GetObjectFormat().EmptyObjectID().String() {
-		if baseCommit, _ := ctx.Repo.GitRepo.GetCommit(ci.BaseBranch); baseCommit != nil {
-			ci.BaseBranch = baseCommit.ID.String()
-			ctx.Data["BaseBranch"] = ci.BaseBranch
-			baseIsCommit = true
-		} else if ci.BaseBranch == ctx.Repo.GetObjectFormat().EmptyObjectID().String() {
 			if isSameRepo {
 				ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadBranch))
 			} else {
 				ctx.Redirect(ctx.Repo.RepoLink + "/compare/" + util.PathEscapeSegments(ci.HeadRepo.FullName()) + ":" + util.PathEscapeSegments(ci.HeadBranch))
 			}
-			return nil
 		} else {
 			ctx.NotFound("IsRefExist", nil)
-			return nil
 		}
+		return nil
 	}
 	ctx.Data["BaseIsCommit"] = baseIsCommit
 	ctx.Data["BaseIsBranch"] = baseIsBranch
@@ -514,15 +508,8 @@ func ParseCompareInfo(ctx *context.Context) *common.CompareInfo {
 	headIsBranch := ci.HeadGitRepo.IsBranchExist(ci.HeadBranch)
 	headIsTag := ci.HeadGitRepo.IsTagExist(ci.HeadBranch)
 	if !headIsCommit && !headIsBranch && !headIsTag {
-		// Check if headBranch is short sha commit hash
+		ctx.NotFound("IsRefExist", nil)
-		if headCommit, _ := ci.HeadGitRepo.GetCommit(ci.HeadBranch); headCommit != nil {
+		return nil
-			ci.HeadBranch = headCommit.ID.String()
-			ctx.Data["HeadBranch"] = ci.HeadBranch
-			headIsCommit = true
-		} else {
-			ctx.NotFound("IsRefExist", nil)
-			return nil
-		}
 	}
 	ctx.Data["HeadIsCommit"] = headIsCommit
 	ctx.Data["HeadIsBranch"] = headIsBranch