Custom detectors running after default detectors

[farski]

We've run into a situation where a lot of MP3 files that we're getting from a particular source include a junk byte that is throwing off file type detection. (They seem to include an extra, unnecessary byte after the ID3 headers, but before FF E0, so the MPEG detector is missing them.)

We're looking to add a slightly more permissive, low priority check that can deal with this junk byte, but not at the risk of breaking any existing detectors, and therefore we'd only want it to run if no other default or custom detectors were successful.

Is that an enhancement that the project would consider?