Tor Browser for Android 1.0a1 signature file missing from dist.torproject.org

on this page: https://www.torproject.org/download/download-easy.html.en#android

I want to check the signature of Tor Browser for Android (TorBrowser-1.0a1) so I click 'sig' underneath.

The hyperlink directs me to a 404 here: https://dist.torproject.org/torbrowser/mobile/1.0a1/TorBrowser-1.0a1.asc

and there appears to be no signature file in this folder: https://dist.torproject.org/torbrowser/mobile/1.0a1/

Trac:
Username: mh