[paneendrakumar0]

Fixes #478.

Problem

Both the name and type attributes of PackageDescriptor are mutable and may be modified after instantiation (for example, during package identification or augmentation). Because __hash__ previously computed hash((self.type, self.name)), mutating either attribute changes the instance's hash value while it resides in a set or dict, corrupting the hash table buckets and causing subsequent membership checks or removal operations to fail:

desc = PackageDescriptor('foo')
descs = {desc}
desc.name = 'bar'
assert desc in descs  # failed

Solution

• Compute __hash__ using os.path.realpath(str(self.path)). The package path is set upon construction and does not change during the descriptor's lifetime.
• This satisfies Python's hash contract: two descriptors that compare equal (__eq__ verifies (self.type, self.name) == (other.type, other.name) and realpath(self) == realpath(other)) will always yield identical hashes.
• Two descriptors sharing the same path but having different types/names produce identical hashes (hash collision), which Python sets and dicts handle through equality probing.
• Added test coverage in test_magic_methods verifying that mutations to name or type preserve hash value and set membership, and that descriptors pointing to the same realpath compare equal and hash identically.