[pantsd] Improve SIGQUIT handling in the thin client. (#5177)
[pantsd] Improve SIGQUIT handling in the thin client. (#5177)

Fixes #5176
tdyas/pants,wisechengyi/pants,pantsbuild/pants,baroquebobcat/pants,UnrememberMe/pants,twitter/pants,jsirois/pants,twitter/pants,pantsbuild/pants,tdyas/pants,pantsbuild/pants,wisechengyi/pants,twitter/pants,baroquebobcat/pants,UnrememberMe/pants,benjyw/pants,baroquebobcat/pants,wisechengyi/pants,UnrememberMe/pants,twitter/pants,benjyw/pants,foursquare/pants,twitter/pants,UnrememberMe/pants,wisechengyi/pants,wisechengyi/pants,pantsbuild/pants,tdyas/pants,foursquare/pants,benjyw/pants,tdyas/pants,baroquebobcat/pants,benjyw/pants,jsirois/pants,twitter/pants,pantsbuild/pants,benjyw/pants,foursquare/pants,tdyas/pants,wisechengyi/pants,benjyw/pants,tdyas/pants,baroquebobcat/pants,foursquare/pants,UnrememberMe/pants,twitter/pants,baroquebobcat/pants,baroquebobcat/pants,tdyas/pants,tdyas/pants,foursquare/pants,foursquare/pants,pantsbuild/pants,twitter/pants,jsirois/pants,baroquebobcat/pants,foursquare/pants,twitter/pants,wisechengyi/pants,tdyas/pants,foursquare/pants,wisechengyi/pants,wisechengyi/pants,baroquebobcat/pants,benjyw/pants,UnrememberMe/pants,UnrememberMe/pants,UnrememberMe/pants,foursquare/pants,pantsbuild/pants,UnrememberMe/pants