e7da5b104d
Commit 79b2366387 added the field `skip`
to support unaligned reads, but set the `offset` field to a wrong
value. This resulted in miscalculation of `remaining`, causing
an assertion failure.
The fix is to assign `offset` the correct value, but consider the
`skip` value in the assertion.
Closes https://github.com/MusicPlayerDaemon/MPD/issues/1067