c_encoding can never be NULL, which allows some code simplification

Python/ast.c

@@ -4002,9 +4002,6 @@ decode_unicode(struct compiling *c, const char *s, size_t len, const char *encod
     char *p;
     const char *end;
 
-    if (encoding == NULL) {
-        u = NULL;
-    } else {
     /* check for integer overflow */
     if (len > PY_SIZE_MAX / 6)
         return NULL;
@@ -4050,7 +4047,7 @@ decode_unicode(struct compiling *c, const char *s, size_t len, const char *encod
     }
     len = p - buf;
     s = buf;
-    }
+
     v = PyUnicode_DecodeUnicodeEscape(s, len, NULL);
     Py_XDECREF(u);
     return v;
@@ -4994,8 +4991,7 @@ parsestr(struct compiling *c, const node *n, int *bytesmode, int *fmode)
             }
         }
     }
-    need_encoding = (!*bytesmode && c->c_encoding != NULL &&
-                     strcmp(c->c_encoding, "utf-8") != 0);
+    need_encoding = !*bytesmode && strcmp(c->c_encoding, "utf-8") != 0;
     if (rawmode || strchr(s, '\\') == NULL) {
         if (need_encoding) {
             PyObject *v, *u = PyUnicode_DecodeUTF8(s, len, NULL);