BUG: Fix format statement associated with AttributeError.

Before this fix, a reference such as `numpy.wxyz` produced an
incorrect error message because of the invalid format specifiers
in the error message string:

    >>> import numpy
    >>> numpy.wxyz
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/.../numpy/__init__.py", line 206, in __getattr__
        "module %s has no attribute $s".format(__name__, attr))
    AttributeError: module %s has no attribute $s

After the fix:

    >>> import numpy
    >>> numpy.wxyz
    Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
      File "/.../numpy/__init__.py", line 206, in __getattr__
        "{!r}".format(__name__, attr))
    AttributeError: module 'numpy' has no attribute 'wxyz'

1 files changed, 2 insertions, 3 deletions

diff --git a/numpy/__init__.py b/numpy/__init__.py
index ae297597e..07d67945c 100644
--- a/numpy/__init__.py
+++ b/numpy/__init__.py
@@ -202,9 +202,8 @@ else:
                 from .testing import Tester
                 return Tester
             else:
-                raise AttributeError(
-                    "module %s has no attribute $s".format(__name__, attr))
-
+                raise AttributeError("module {!r} has no attribute "
+                                     "{!r}".format(__name__, attr))
 
         def __dir__():
             return __all__ + ['Tester', 'testing']