Changed master label test to strictly enforce format.

Review: https://reviews.apache.org/r/28293
Changed slave label test to strictly enforce format.

Review: https://reviews.apache.org/r/28294
Match future dispatch messages with type info.

Review: https://reviews.apache.org/r/28052
Fixed future dispatch in tests to match function type.

Review: https://reviews.apache.org/r/28081