Do not store local testresults on Travis run.

.travis.yml

@@ -15,6 +15,6 @@ before_install:
 install:
   - pip install -r requirements.txt --use-mirrors
 # command to run tests
-script: make test
+script: make test PYTESTOPTS=-s
 #notifications:
 #  email: false

Makefile

@@ -22,7 +22,7 @@ endif
 # Pytest options:
 # --resultlog: write test results in file
 # -s: do not capture stdout/stderr (some tests fail otherwise)
-PYTESTOPTS:=--resultlog=testresults.txt -s --durations=0
+PYTESTOPTS?=--resultlog=testresults.txt -s --durations=0
 # which test modules to run
 TESTS ?= tests/
 # set test options