Return 204 instead of error when commit not exist

Fix #31976

Author: AdamMajer

routers/api/v1/repo/commits.go

@@ -144,6 +144,8 @@ func GetAllCommits(ctx *context.APIContext) {
 	// responses:
 	//   "200":
 	//     "$ref": "#/responses/CommitList"
+	//   "204":
+	//     "description": "StatusNoContents indicates no commits found matching particular SHA"
 	//   "404":
 	//     "$ref": "#/responses/notFound"
 	//   "409":
@@ -195,6 +197,10 @@ func GetAllCommits(ctx *context.APIContext) {
 			// get commit specified by sha
 			baseCommit, err = ctx.Repo.GitRepo.GetCommit(sha)
 			if err != nil {
+				if git.IsErrNotExist(err) {
+					ctx.Status(http.StatusNoContent)
+					return
+				}
 				ctx.Error(http.StatusInternalServerError, "GetCommit", err)
 				return
 			}