Merge pull request #9289 from 0xc0170/test_travis

travis: add keys for ubuntu - workaround

.travis.yml

@@ -46,6 +46,8 @@ before_install:
   # Setup ppa to make sure arm-none-eabi-gcc is correct version
   - sudo add-apt-repository -y ppa:team-gcc-arm-embedded/ppa
   - sudo add-apt-repository -y ppa:deadsnakes/ppa
+  # workaround for https://travis-ci.community/t/then-sudo-apt-get-update-failed-public-key-is-not-available-no-pubkey-6b05f25d762e3157-in-ubuntu-xenial/1728
+  - sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 762E3157
   # Loop until update succeeds (timeouts can occur)
   - travis_retry $(! sudo apt-get update 2>&1 |grep Failed)