As discussed on the mailing list https://groups.google.com/forum/#!topic/bazel-discuss/UKLK7Y-jsW4 the protobuf repo is notoriously sensitive to recompilation. Presumably something in the environment used in the action key for protobuf C++ compilation leads to cache invalidation and hence recompiling protobuf from source.

Given protobuf libs are often base dependencies for many others, leads to degraded user experience.

Repro steps include taking any workspace that has a proto dependency and source ~/.bashrc, watch protobuf recompile.

Observed up to and including bazel 0.20.0.

/assign @hlopko