Why I get Forbidden when trying to install drush on Travis CI via composer?

Question

This composer command fails on my Travis CI project (example failed build):

composer global require drush/drush:dev-master

It fails with:

The 'https://api.github.com/repos/RobLoach/Console_Table/zipball/9f80c91a9fc01a3cce71ae80ea5bd473cb0eba4c'
URL could not be accessed: HTTP/1.1 403 Forbidden

although that file can be downloaded just fine.

The .travis.yml file is here

Answer 1

I added

composer selfupdate

to the .travis.yml file and now that build step passes. Not sure if that really fixed the problem or if this will happen again as random fail.