hashlib suddenly broken

[Larry Martell]

I am on a mac running 10.8.5, python 2.7

Suddenly, many of my scripts started failing with:

ValueError: unsupported hash type sha1

Googling this showed that it's an issue with hashlib with a common
cause being a file called hashlib.py that gets in the way of the
interpreter finding the standard hashlib module, but that doesn't seem
to be the case:

>>> import hashlib
ERROR:root:code for hash sha1 was not found.
Traceback (most recent call last):
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/hashlib.py",
line 139, in <module>
    globals()[__func_name] = __get_hash(__func_name)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/hashlib.py",
line 103, in __get_openssl_constructor
    return __get_builtin_constructor(name)
  File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/hashlib.py",
line 91, in __get_builtin_constructor
    raise ValueError('unsupported hash type %s' % name)
ValueError: unsupported hash type sha1

And that file has not changed any time recently:

$ ls -l /System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/hashlib.py
-rw-r--r--  1 root  wheel  5013 Apr 12  2013
/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/hashlib.py

This just started happening yesterday, and I cannot think of anything
that I've done that could cause this.