Remove unused Task._build_invalidator root param. (#6308)
Remove unused Task._build_invalidator root param. (#6308)

Fixes #4697
wisechengyi/pants,pantsbuild/pants,twitter/pants,twitter/pants,tdyas/pants,jsirois/pants,benjyw/pants,benjyw/pants,wisechengyi/pants,twitter/pants,tdyas/pants,benjyw/pants,pantsbuild/pants,twitter/pants,tdyas/pants,twitter/pants,pantsbuild/pants,pantsbuild/pants,twitter/pants,tdyas/pants,jsirois/pants,tdyas/pants,wisechengyi/pants,twitter/pants,wisechengyi/pants,pantsbuild/pants,pantsbuild/pants,tdyas/pants,jsirois/pants,benjyw/pants,benjyw/pants,tdyas/pants,wisechengyi/pants,tdyas/pants,wisechengyi/pants,wisechengyi/pants,wisechengyi/pants,pantsbuild/pants,wisechengyi/pants,twitter/pants,benjyw/pants,twitter/pants,benjyw/pants,tdyas/pants