Issue #10914: Initialize correctly the filesystem codec when creating a new

subinterpreter to fix a bootstrap issue with codecs implemented in Python, as
the ISO-8859-15 codec.

Add fscodec_initialized attribute to the PyInterpreterState structure.

Python/pythonrun.c

@@ -53,7 +53,7 @@ extern grammar _PyParser_Grammar; /* From graminit.c */
 
 /* Forward */
 static void initmain(void);
-static void initfsencoding(void);
+static int initfsencoding(PyInterpreterState *interp);
 static void initsite(void);
 static int initstdio(void);
 static void flush_io(void);
@@ -291,7 +291,8 @@ Py_InitializeEx(int install_sigs)
 
     _PyTime_Init();
 
-    initfsencoding();
+    if (initfsencoding(interp) < 0)
+        Py_FatalError("Py_Initialize: unable to load the file system codec");
 
     if (install_sigs)
         initsigs(); /* Signal handling stuff, including initintr() */
@@ -608,6 +609,10 @@ Py_NewInterpreter(void)
         Py_DECREF(pstderr);
 
         _PyImportHooks_Init();
+
+        if (initfsencoding(interp) < 0)
+            goto handle_error;
+
         if (initstdio() < 0)
             Py_FatalError(
             "Py_Initialize: can't initialize sys standard streams");
@@ -720,8 +725,8 @@ initmain(void)
     }
 }
 
-static void
-initfsencoding(void)
+static int
+initfsencoding(PyInterpreterState *interp)
 {
     PyObject *codec;
 #if defined(HAVE_LANGINFO_H) && defined(CODESET)
@@ -738,7 +743,8 @@ initfsencoding(void)
 
         Py_FileSystemDefaultEncoding = codeset;
         Py_HasFileSystemDefaultEncoding = 0;
-        return;
+        interp->fscodec_initialized = 1;
+        return 0;
     }
 #endif
 
@@ -748,10 +754,11 @@ initfsencoding(void)
         /* Such error can only occurs in critical situations: no more
          * memory, import a module of the standard library failed,
          * etc. */
-        Py_FatalError("Py_Initialize: unable to load the file system codec");
-    } else {
-        Py_DECREF(codec);
+        return -1;
     }
+    Py_DECREF(codec);
+    interp->fscodec_initialized = 1;
+    return 0;
 }
 
 /* Import the site module (not into __main__ though) */