Bluetooth difficulties with rAudio on RPi 1

[vale-max]

had some issues with bluetooth, on RPi1 in case it matters...
First thing is that the bluetooth service was not enabled after installation, and bluetoothctl hangs when the service is not started.
Solved simply with "systemctl enable bluetooth" however I'm reporting it as I do not know if the service was meant to be disabled or not.

The second difficulty was that my Android 10 phone kept asking for a PIN and whatever I tried the connection failed with wrong pin error.
On rAudio this error was logged:

Jan 04 17:41:32 rune bluetoothd[854]: src/agent.c:pincode_reply() Agent /test/autoagent replied with an error: org.freedesktop.DBus.Error.UnknownMethod, Traceback (most recent call last):
                                        File "/usr/lib/python3.9/site-packages/dbus/service.py", line 658, in _message_cb
                                          (candidate_method, parent_method) = _method_lookup(self, method_name, interface_name)
                                        File "/usr/lib/python3.9/site-packages/dbus/service.py", line 248, in _method_lookup
                                          raise UnknownMethodException('%s is not a valid method of interface %s' % (method_name, dbus_interface))
                                      dbus.exceptions.UnknownMethodException: org.freedesktop.DBus.Error.UnknownMethod: Unknown method: RequestPinCode is not a valid method of interface org.bluez.Agent1

I could not understand why it asked for a PIN as the agent capability (NoInputNoOutput) seems to be correct, so I quickly added three lines to /srv/http/bash/bluezdbus.py:

diff bluezdbus.py.orig bluezdbus.py
48a49,53
 
>     @dbus.service.method(AGENT_INTERFACE, in_signature="o", out_signature="s")
>     def RequestPinCode(self, device):
>         return ("0000")
> 
>

This way "0000" works as a PIN and the pairing is completed without errors.