DynamicsTest.compareEquationsOfMotion fails sporadically

[jslee02]

Bug Report

Please answer the following questions for yourself before reporting a bug.

• [x] I checked the documentation and found no answer.
• [x] I checked to make sure that this issue has not already been filed.

Environment

Select the following information.

• DART version: master
• OS name and version name(or number): macOS High Sierra
• Compiler name and version number: AppleClang 9.1.0

Expected Behavior

DynamicsTest.compareEquationsOfMotion test passes

Current Behavior

Failed on Travis CI: https://travis-ci.org/dartsim/dart/jobs/525941629#L1044