all: Audit gitignore Contents
all: Audit gitignore Contents

Problem / Solution

Our open source project gitignore files have accumulated quite a bit of
cruft. Let's unify them, remove no longer necessary entries, and call
out project specific items.

JIRA Issues: CSL-7911

Differential Revision: https://phabricator.twitter.biz/D311962

twitter/util,twitter/util,twitter/util