Translate AWS Rate limiting errors to 502 errors#5270

Merged

catsby merged 4 commits intomasterfrom aws-upstream-ratelimiting

Sep 18, 2018

+2,030-121

Commits on Sep 7, 2018

Initial implemntation of returning 529 for rate limits
catsby
committed

Commits on Sep 11, 2018

refactor locking and unlocking into methods on *backend
catsby
committed

Commits on Sep 12, 2018

refactor/simply the locking
catsby
committed

Commits on Sep 18, 2018

check client after grabbing lock
catsby
committed