Update to upstream version '0.0.60'
with Debian dir e539ea7a60cb91c2d7ac920492493b9cdf43fc33

This will allow deduplicating code across loaders.

This generates more realistic contents and avoids spurious HashCollisions when
generating a set of objects using these hypothesis strategies, at the cost of
slightly worse "boundary checking" (i.e. we won't check contents with a length >
4096 bytes).

This lets us generate Content objects directly from a bytestring, with the
proper set of hashes auto-generated from the contents.

Update to upstream version '0.0.59'
with Debian dir b29a4e120d6f24180eb5e25a7728c43d443c41b7

Update to upstream version '0.0.57'
with Debian dir b6fefac634efaca283f481b553074b3c49c16e6e

Required by loaders, when they can't parse the fullname.

Will be used by loaders.

It just makes more sense that way.

eg. before this change, all leafs would be equal to each other.

They will be used by loaders, so they can deal only with
model objects, instead of having to do the same conversion themselves.

This removes the `data` and `save_path` arguments of `from_file` and
`from_disk`, as data loading is always deferred from now on.
To access it, users are now expected to either open the data files
themselves, or us `.to_model().with_data()`.

Regular files were created, as the 'mode' argument of os.mknod was missing.
However, creating devices requires root; so we can't reasonably do that in
tests.

Instead, we're using /dev/null instead of creating one.
And while we're at it, let's also use /dev/zero (which, if not handled
properly, will result in an infinite read).

It should be cheap enough to do it, and it makes tests easier.

It will be useful to loaders, as they currently load the entire
content in memory before deciding to skip it.

This allows the `swh identify` command to work again.

Close T2288

Can be useful to deduplicate code in swh-storage.

Update to upstream version '0.0.56'
with Debian dir e8fdc7e23d26a4e0a0e61c22110e23037624b29b

It already is in practice.

Update to upstream version '0.0.55'
with Debian dir 757a1994777f26411a82369bb5efa044e815d8eb

The current postgresql model refuses NULL values.

Update to upstream version '0.0.54'
with Debian dir bfe97b183746e3dc69c02c2e023a1b921944ae16