Change the flow control logic to be more clear

[rkruze]

The previous code was highlighted by PMD - https://pmd.github.io/pmd-5.6.1/pmd-java/rules/java/basic.html#AvoidBranchingStatementAsLastInLoop

[cockroach-teamcity]

This change is 

[cockroach-teamcity]

http://cockroach-docs-review.s3-website-us-east-1.amazonaws.com/4be97c3499bae58dac01e54be0e8a2e65a6fb875/

[jseldess]

Thanks, @rkruze! I'll get a dev to review.

[BramGruneir]

Code change LGTM.