FLAC objects that compare equal do not have the same hash value

[mahkitah]

When you create two FLAC objects from the same file, they compare equal but they do not have the same hash value.
This is annoying when, for instance, you use sets to find duplicates. And it also goes against python 'regulations':

from Python docs
"The only required property is that objects which compare equal have the same hash value"

This issue may also apply to other types, but I only tested this for FLAC.

>>> from mutagen.flac import FLAC
>>> path = "myflac.flac"
>>> f1 = FLAC(path)
>>> f2 = FLAC(path)
>>> f1 == f2
True
>>> hash(f1) == hash(f2)
False