Fix PYTHONIOENCODING parsing error and re-enable assertion in test_sys#test_exit

Author: steve-s

graalpython/com.oracle.graal.python.test/src/tests/unittest_tags/test_sys.txt

@@ -27,6 +27,8 @@
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_refcount
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_setrecursionlimit_recursion_depth
 *graalpython.lib-python.3.test.test_sys.SysModuleTest.test_sys_getwindowsversion_no_instantiation
+*graalpython.lib-python.3.test.test_sys.SysModuleTest.test_c_locale_surrogateescape
+*graalpython.lib-python.3.test.test_sys.SysModuleTest.test_posix_locale_surrogateescape
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_custom_unraisablehook
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_custom_unraisablehook_fail
 *graalpython.lib-python.3.test.test_sys.UnraisableHookTest.test_original_unraisablehook

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/builtins/modules/GraalPythonModuleBuiltins.java

@@ -125,13 +125,16 @@ public void initialize(PythonCore core) {
         builtinConstants.put("is_native", TruffleOptions.AOT);
         PythonContext ctx = core.getContext();
         String encodingOpt = ctx.getLanguage().getEngineOption(PythonOptions.StandardStreamEncoding);
-        String standardStreamEncoding;
-        String standardStreamError;
+        String standardStreamEncoding = null;
+        String standardStreamError = null;
         if (encodingOpt != null && !encodingOpt.isEmpty()) {
             String[] parts = encodingOpt.split(":");
-            standardStreamEncoding = parts[0].isEmpty() ? "utf-8" : parts[0];
-            standardStreamError = parts.length > 1 && !parts[1].isEmpty() ? parts[1] : "strict";
-        } else {
+            if (parts.length > 0) {
+                standardStreamEncoding = parts[0].isEmpty() ? "utf-8" : parts[0];
+                standardStreamError = parts.length > 1 && !parts[1].isEmpty() ? parts[1] : "strict";
+            }
+        }
+        if (standardStreamEncoding == null) {
             standardStreamEncoding = "utf-8";
             standardStreamError = "surrogateescape";
         }

graalpython/lib-python/3/test/test_sys.py

@@ -169,10 +169,9 @@ def check_exit_message(code, expected, **env_vars):
 
         # test that the exit message is written with backslashreplace error
         # handler to stderr
-        # TODO: GraalPython patch, will be fixed by proper implementation of backslashreplace handler (GR-10256)
-        # check_exit_message(
-        #     r'import sys; sys.exit("surrogates:\uDCFF")',
-        #     b"surrogates:\\udcff")
+        check_exit_message(
+            r'import sys; sys.exit("surrogates:\uDCFF")',
+            b"surrogates:\\udcff")
 
         # test that the unicode message is encoded to the stderr encoding
         # instead of the default encoding (utf8)