"ROOT=/some/dir emerge -1 shared-mime-info" will update the mime db under /, not under /some/dir. Reproducible: Always Steps to Reproduce:
Created attachment 74353 [details, diff] Patch for fdo-mime. The problem comes from partial support for $ROOT in fdo-mime.eclass. Patch enclosed.
correct. We probably also want to make sure we actually use the update-* bins in ${ROOT}.
My apologies for the delay. Fixed the eclass after some local testing, please test. Thanks for the report.