correct run_entries bug with core option

run_entries.py

@@ -14,7 +14,7 @@ parser.add_argument("-m", "--mem", nargs="?", const=8,
                     help="Maximum amount of memory used for the different tests. Should be written as <number><unit> where <unit> may be nothing, K, M or G, e.g. 100M")
 parser.add_argument("-n", action='store_true',
                     help="To only run benchmarks not previously done")
-parser.add_argument("-c", "--core", nargs="?", const="1", default="1",
+parser.add_argument("-c", "--core", nargs="?", const="1",
                     help="Core on which the job should be ran")
 args = parser.parse_args()
 
@@ -46,4 +46,4 @@ for i, pkg_name in enumerate(pkg_list):
             assert not info["script error"]
         except:
             subprocess.run(["python3", "run_test.py", str(pkg_path), str(("data" / Path(data_path)).with_suffix(".json"))] + ["--timeout", str(args.timeout)]*(
-                args.timeout != None) + ["--mem", str(args.mem)]*(args.mem != None) + ["--perf"]*args.perf + ["--core", args.core])
+                args.timeout != None) + ["--mem", str(args.mem)]*(args.mem != None) + ["--perf"]*args.perf + ["--core", args.core]*(args.core != None))