Fixed #1403 where compileall and py_compile choked on an encoding header in a py…

Fixed #1403 where compileall and py_compile choked on an encoding header in a py file. Both modules need more unit tests.

Lib/io.py

@@ -1063,6 +1063,9 @@ class TextIOWrapper(TextIOBase):
                 else:
                     encoding = locale.getpreferredencoding()
 
+        if not isinstance(encoding, str):
+            raise ValueError("invalid encoding: %r" % encoding)
+
         self.buffer = buffer
         self._encoding = encoding
         self._readuniversal = not newline

Lib/py_compile.py

@@ -88,7 +88,7 @@ def read_encoding(file, default):
                 break
             m = re.match(r".*\bcoding:\s*(\S+)\b", line)
             if m:
-                return str(m.group(1))
+                return m.group(1).decode("ascii")
         return default
     finally:
         f.close()