At arraymodule.c (line 1258):

		nread = fread(item + (Py_SIZE(self) - n) * itemsize,
			      itemsize, n, fp);
		if (nread < (size_t)n) {
		  Py_SIZE(self) -= (n - nread);
			PyMem_RESIZE(item, char, Py_SIZE(self)*itemsize);
			self->ob_item = item;
			self->allocated = Py_SIZE(self);
			PyErr_SetString(PyExc_EOFError,
				         "not enough items in file");
			return NULL;
		}

When fread returns 0, ferror should be called to check if it was an EOF
or an error condition. It is not handling OSErrors, such as I/O errors,
raising always "not enough items in file".