Issue #25523: Merge "a" to "an" fixes from 3.4 into 3.5

Modules/_io/_iomodule.c

@@ -75,7 +75,7 @@ PyDoc_STRVAR(module_doc,
 "Another IOBase subclass, TextIOBase, deals with the encoding and decoding\n"
 "of streams into text. TextIOWrapper, which extends it, is a buffered text\n"
 "interface to a buffered raw stream (`BufferedIOBase`). Finally, StringIO\n"
-"is a in-memory stream for text.\n"
+"is an in-memory stream for text.\n"
 "\n"
 "Argument names are not part of the specification, and only the arguments\n"
 "of open() are intended to be used as keyword arguments.\n"

Modules/_io/textio.c

@@ -905,8 +905,8 @@ _io_TextIOWrapper___init___impl(textio *self, PyObject *buffer,
         if (self->encoding == NULL) {
           catch_ImportError:
             /*
-             Importing locale can raise a ImportError because of
-             _functools, and locale.getpreferredencoding can raise a
+             Importing locale can raise an ImportError because of
+             _functools, and locale.getpreferredencoding can raise an
              ImportError if _locale is not available.  These will happen
              during module building.
             */