python/find_rsa_pkcs1v15_modulus: fix compatibility with Python2 and old PyCrypto
python/find_rsa_pkcs1v15_modulus: fix compatibility with Python2 and old PyCrypto

Python2 uses IOError instead of OSError when open() raises an exception
because a file has not been found.

Old PyCrypto uses Crypto.Hash.SHA and does not have Crypto.Hash.SHA1.

fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared,fishilico/shared