simplify test script

.travis.yml

@@ -17,6 +17,7 @@ matrix:
             - libssl-dev
     - python: 2.7
       env: DOCS=1
+      script: 'cd docs && make html'
     - python: pypy
     - python: pypy
       env: OPENSSL=1.0.2
@@ -40,8 +41,7 @@ before_script:
   - "openssl version -a"
 
 script:
-  - "if [ -z \"$DOCS\" ]; then nosetests --with-cov --cov-report term-missing; fi"
-  - "if [ -n \"$DOCS\" ]; then cd docs && make html; fi"
+  - "nosetests --with-cov --cov-report term-missing"
 
 after_success:
   - coveralls