Right now, an extension that fails to install -- for example, due to a signature error -- will not be retried (AFAICT). This interacts with distributions, which cannot set the xpinstall.signatures.dev-root=true pref early enough to install distribution extensions that are signed with the staging certificate on first run, and then won't get extensions on later runs after the pref is set.

This is https://bugzilla.mozilla.org/show_bug.cgi?id=1551455#c6.

Permalink to where we set it.

https://searchfox.org/mozilla-central/rev/2022d34edd5817948b27f093cd203ae6adb18a25/toolkit/mozapps/extensions/internal/XPIInstall.jsm#3952

I'm not sure how this is going to work, though, because installAddon just copies the addon and doesn't return any errors:

https://searchfox.org/mozilla-central/rev/2022d34edd5817948b27f093cd203ae6adb18a25/toolkit/mozapps/extensions/internal/XPIInstall.jsm#3209