bugfix: Do not run spack spec in the test environment for Python 2.6

- Trying to get our Python 2.6 tests working again.
- This seems to crash travis in the 2.6 environment, for whatever reason.

share/spack/qa/run-unit-tests

@@ -31,7 +31,9 @@ ${coverage_run} bin/spack -h
 ${coverage_run} bin/spack help -a
 
 # Profile and print top 20 lines for a simple call to spack spec
-${coverage_run} bin/spack -p --lines 20 spec mpileaks%gcc ^elfutils@0.170
+if [[ $TRAVIS_PYTHON_VERSION != 2.6 ]]; then
+    ${coverage_run} bin/spack -p --lines 20 spec mpileaks%gcc ^elfutils@0.170
+fi
 
 # Run unit tests with code coverage
 extra_args=""