Weekly channel will serve 3.50
Quarterly channel will serve 3.49
Exact version numbers can be specified as v=3.50, v=3.49, v=3.48, or v=3.47.
Version 3.46 will be decommissioned.
If you don't specify a version (or request a retired version), you will be served a default version, which depending on your key configuration will be either 3.49 or 3.50. But a developer specified version will always be honored and served when requested when it's an existing version.
To report issues with any version of the API, see:https://issuetracker.google.com/savedsearches/558438