Snapcraft auto build service failing

I have Olivia github repo set to auto build on build.snapcraft.io it was working fine till tomorrow and now am getting these build errors…

Setting up software-properties-common (0.96.20.8) …
Processing triggers for libc-bin (2.23-0ubuntu11) …
[02/Aug/2019:19:55:24 +0000] “CONNECT launchpad.net:443 HTTP/1.0” 200 9202 “-” “-”
[02/Aug/2019:19:55:24 +0000] “CONNECT launchpad.net:443 HTTP/1.0” 200 9202 “-” “-”
gpg: keyring /tmp/tmpmwt7156t/secring.gpg' created gpg: keyring /tmp/tmpmwt7156t/pubring.gpg’ created
gpg: requesting key ED8E640A from hkp server keyserver.ubuntu.com
[02/Aug/2019:19:55:24 +0000] “GET http://keyserver.ubuntu.com:80/pks/lookup?op=get&options=mr&search=0x8E51A6D660CD88D67D65221D90BD7EACED8E640A HTTP/1.0” 403 1919 “-” “-”
gpgkeys: key 8E51A6D660CD88D67D65221D90BD7EACED8E640A can’t be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
gpg: keyserver communications error: keyserver helper general error
gpg: keyserver communications error: unknown pubkey algorithm
gpg: keyserver receive failed: unknown pubkey algorithm
Failed to add key.
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Downloading parts list
Failed to run ‘override-pull’: Exit code was 1.
Build failed
Traceback (most recent call last):
File “/usr/lib/python2.7/dist-packages/lpbuildd/target/build_snap.py”, line 267, in run
self.pull()
File “/usr/lib/python2.7/dist-packages/lpbuildd/target/build_snap.py”, line 233, in pull
env=env)
File “/usr/lib/python2.7/dist-packages/lpbuildd/target/build_snap.py”, line 104, in run_build_command
return self.backend.run(args, env=full_env, **kwargs)
File “/usr/lib/python2.7/dist-packages/lpbuildd/target/lxd.py”, line 502, in run
subprocess.check_call(cmd, **kwargs)
File “/usr/lib/python2.7/subprocess.py”, line 541, in check_call
raise CalledProcessError(retcode, cmd)
CalledProcessError: Command ‘[‘lxc’, ‘exec’, ‘lp-xenial-amd64’, ‘–env’, ‘LANG=C.UTF-8’, ‘–env’, ‘SHELL=/bin/sh’, ‘–env’, ‘SNAPCRAFT_LOCAL_SOURCES=1’, ‘–env’, ‘SNAPCRAFT_SETUP_CORE=1’, ‘–env’, ‘SNAPCRAFT_BUILD_INFO=1’, ‘–env’, ‘SNAPCRAFT_IMAGE_INFO={“build-request-id”: “lp-50609618”, “build-request-timestamp”: “2019-08-02T19:52:29Z”, “build_url”: “https://launchpad.net/~build.snapcraft.io/+snap/1ad2f4d46093b6fdff0f98279b385b15/+build/635489”}’, ‘–env’, ‘SNAPCRAFT_BUILD_ENVIRONMENT=host’, ‘–env’, ‘http_proxy=http://10.10.10.1:8222/’, ‘–env’, ‘https_proxy=http://10.10.10.1:8222/’, ‘–env’, ‘GIT_PROXY_COMMAND=/usr/local/bin/snap-git-proxy’, ‘–’, ‘/bin/sh’, ‘-c’, ‘cd /build/olivia-test && linux64 snapcraft pull’]’ returned non-zero exit status 2
Revoking proxy token…

my snapcraft.yaml is located here

the code in snapcraft,yaml where one might look is this (as build log shows error here in override-pull step)

ppa:
     plugin: nil
     override-pull: |
       apt --yes install software-properties-common apt-utils
       add-apt-repository -yu ppa:mc3man/mpv-tests

seems like the issue is caused due to the verification of gpg key of repo in ppa step. I compared the failed log with older logs and found difference here -

in failed build:

keyring/tmp/tmpmwt7156t/pubring.gpg’ created
gpg: requesting key ED8E640A from hkp server keyserver.ubuntu.com
[02/Aug/2019:19:55:24 +0000] “GET http://keyserver.ubuntu.com:80/pks/lookup?op=get&options=mr&search=0x8E51A6D660CD88D67D65221D90BD7EACED8E640A HTTP/1.0” 403 1919 “-” “-”
gpgkeys: key 8E51A6D660CD88D67D65221D90BD7EACED8E640A can’t be retrieved
gpg: no valid OpenPGP data found.
gpg: Total number processed: 0
gpg: keyserver communications error: keyserver helper general error
gpg: keyserver communications error: unknown pubkey algorithm
gpg: keyserver receive failed: unknown pubkey algorithm
Failed to add key.

in success build:

gpg: keyring `/tmp/tmpm6qys50x/pubring.gpg' created
gpg: requesting key ED8E640A from hkp server keyserver.ubuntu.com
[29/Jul/2019:20:42:19 +0000] "GET http://keyserver.ubuntu.com:80/pks/lookup?op=get&options=mr&search=0x8E51A6D660CD88D67D65221D90BD7EACED8E640A HTTP/1.0" 200 841 "-" "-"
gpg: /tmp/tmpm6qys50x/trustdb.gpg: trustdb created
gpg: key ED8E640A: public key "Launchpad PPA for Doug McMahon" imported
gpg: no ultimately trusted keys found
gpg: Total number processed: 1
gpg:               imported: 1  (RSA: 1)
OK

How can i fix this key issue ? server is looking keys at same location http://keyserver.ubuntu.com/pks/lookup?op=get&options=mr&search=0x8E51A6D660CD88D67D65221D90BD7EACED8E640A but before it was importing key and now its not :neutral_face: