Segmentation fault: 11 running Xcode unit tests using xctool

Segmentation fault: 11 running Xcode unit tests using xctool

I'm trying to use xctool to run my Xcode unit tests from a Jenkins server
for CI purposes. When I run my tests via:
xctool -project MyApp.xcodeproj -scheme MyApp test -sdk iphonesimulator
I get the following error:
/Users/Shared/Jenkins/Library/Developer/Xcode/DerivedData/MyApp-fxgsgucvulucjcbkdjllermhnvah/Build/Intermediates/MyApp.build/Debug-iphonesimulator/MyAppTests.build/Script-FA92AE8E162C5E1900A410A1.sh:
line 3: 10301 Segmentation fault: 11
"${SYSTEM_DEVELOPER_DIR}/Tools/RunUnitTests"
Command /bin/sh failed with exit code 139
If I remove the default Run Script that has:
# Run the unit tests in this test bundle.
"${SYSTEM_DEVELOPER_DIR}/Tools/RunUnitTests"
from my Test target, the call to xctool works fine -- and I can still run
my unit tests directly in Xcode via Cmd+U.
I've waded through a lot of searches trying to find the "correct" solution
to this but haven't had any luck. Is simply removing that default post
build step that calls RunUnitTests acceptable? What does that even do?