Disallow mutation of values being iterated by a for loop or comprehension
Disallow mutation of values being iterated by a for loop or comprehension

This entails adding a read-locking mechanism to Mutability contexts.

RELNOTES[INC]: Updating list/dicts while they are being looped over is not allowed. Use an explicit copy if needed ("for x in list(mylist):").

--
MOS_MIGRATED_REVID=134442701

davidzchen/bazel-website,bazelbuild/bazel-website,bazelbuild/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website,davidzchen/bazel-website,bazelbuild/bazel-website