With import_delete enabled and performing a re-import (which moves files), the
former location of the file would be "deleted". This would lead to a "file does
not exist" error.
Previously, the thinking went that if the MB database didn't have a length, we
should penalize the track maximally in order to avoid prioritizing a bad match
just because its information was incomplete. As it turns out, though, missing
track lengths are pretty common and this was causing more problems than it was
solving; this way, mysteriously high distances won't appear.
I saw this *extremely* intermittently (and wasn't able to reproduce it at all),
but I think there was a race when invalidating an output queue in the abort()
method of PipelineThread. It was possible for a thread's input queue to be
invalidated (with val=None) while abort_flag was False (and abort_lock was not
held). This would cause coroutines to see a None value when the pipeline was
shutting down. Always poisoning a queue when it's invalidated should solve this
by making the thread break before sending the value to the coroutine.
When a partial match is found, its first item (task.items[0]) may be None, and
_infer_album_fields would crash in this case. This solution walks through the
items list and finds the first non-None item.
Previously, an empty argument was treated as "not an argument at all". Now,
every function call always has at least one argument -- i.e., %foo{} is a
function call whose only argument is "" -- and %foo{,bar} is valid syntax.
This was causing a problem with situation where }} would have semantic meaning
other than escaping a }. Specifically, %func{%func{arg}} contains a }} but
should not escape the }. $} seems to cover this situation. However, ${ is not
permitted as an escape sequence because it looks like the beginning of a symbol
(variable reference) like ${foo}. This is OK because { can be used anywhere as a
literal.
