New MIME detection script breaks uploads for .wav files

[kennithnichol]

The new MIME detection script introduced in rev=39831 has an unexpected side-effect which causes the mime type for uploaded .wav files (audio/wav) to return as 'audio/x-wav' which ultimately causes the upload to fail and declare the file as a security risk.

/wp-includes/functions.php @ line 2324

This affects the most recent security update pushed out to versions 4.6.2 and 4.7.1

https://core.trac.wordpress.org/browser/trunk/src/wp-includes/functions.php?rev=39831&order=name

[Ipstenu]

Thank you! We're already tracking this in #39550 :)