firefox: cannot install a nightly build

[cheggerdev]

When trying to install a nightly build from https://requestpolicy.256k.de/requestpolicy-nightly.xpi
Firefox refuses the installation of it.
In the browser console I see these messages:

1540478526223 addons.xpi WARN Add-on rpcontinued@non-amo.requestpolicy.org is not correctly signed.
1540478526224 addons.xpi WARN Add-on rpcontinued@non-amo.requestpolicy.org is not correctly signed.
1540478526225 addons.xpi WARN Download of https://requestpolicy.256k.de/requestpolicy-nightly.xpi failed: signature is required but missing

Browser and Add-ons:

• Browser: Firefox 56.0.2 on MacOS X
• RequestPolicy version: nightly build

In about:config xpinstall.signatures.required is set to false

RequestPolicy settings:

• Default policy: "deny"

Steps to reproduce:

1. Open a browser tab with URL https://requestpolicy.256k.de/requestpolicy-nightly.xpi
2. Firefox tells you it rejected the installation

[myrdd]

* 62.0.2 on MacOS X

to quote the readme:

Firefox 57+ is not yet supported

[cheggerdev]

Sorry, my mistake. It is 56.0.2. Fixed version number.

[myrdd]

okay I'll look into it

RequestPolicy version: nightly build

FTR this currently is v1.0.beta14.0.2471.rd5be2cd9c.pre

[myrdd]

I can confirm that the latest nightly RPC build (v1.0.beta14.0.2471.rd5be2cd9c.pre) cannot be installed on Firefox, even on versions prior to v57! Looks like the signature of add-ons signed on https://addons.thunderbird.net/ (ATN) is not accepted on Firefox, hence the failure.

I highly recommend you to use SeaMonkey instead of unmaintained Firefox versions.

This is kind of a duplicate of #704, but I'll keep the issue open, at least for reference.