Closes python#25360: Merged fix from 3.5.

Author: vsajip

PC/launcher.c

@@ -1255,7 +1255,7 @@ path '%ls'", command);
                              * is no version specification.
                              */
                             debug(L"searching PATH for python executable\n");
-                            cmd = find_on_path(L"python");
+                            cmd = find_on_path(PYTHON_EXECUTABLE);
                             debug(L"Python on path: %ls\n", cmd ? cmd->value : L"<not found>");
                             if (cmd) {
                                 debug(L"located python on PATH: %ls\n", cmd->value);