My take on the "Cannot add the specified assembly to the global assembly cache (...)" issue

I got this when updating a WSP, on a SharePoint 2013 server. Tried the suggested IISReset, Timer Service restart... no luck. This however worked like a charm:

[System.EnterpriseServices.Internal.Publish] $publish = new-object System.EnterpriseServices.Internal.Publish
$publish.GacRemove("c:\windows\microsoft.net\assembly\remaining-path-to-trouble.dll")