test: test intended code-paths
test: test intended code-paths

The tests did not agree with the test comments. Tests first and second
were both testing the !state.reading case. Now second tests the
state.reading && state.length case.

Fixes joyent/node#5183

dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node,dreamllq/node