Initialize user agent to fix a web doc generation error (#1026)
Initialize user agent to fix a web doc generation error (#1026)

* Fix linter import order warning

* Fix unreachable code linter error

Since `raise` stops execution, sys.exit(1) was never reached.

* Initialize USER_AGENT to fix doc generation error

* Fix yapf formatting error

Co-authored-by: Ross Rauber <9ef671d5eeffca37600df5d071e31cce9a94f384@google.com>
GoogleCloudPlatform/gsutil,GoogleCloudPlatform/gsutil