Travis: Use separate target to calculate coverage

.travis.yml

@@ -15,6 +15,7 @@ env:
     - TOXENV=flake8
     - TOXENV=flakeplus
     - TOXENV=apicheck
+    - TOXENV=cov
 install: travis_retry pip install -U tox
 script: tox -v -- -v
 after_success:

tox.ini

@@ -1,5 +1,5 @@
 [tox]
-envlist = 2.7,pypy,3.4,3.5,pypy3,flake8,flakeplus,apicheck
+envlist = 2.7,pypy,3.4,3.5,pypy3,flake8,flakeplus,apicheck,cov
 
 [testenv]
 sitepackages = False
@@ -9,16 +9,16 @@ deps=
     -r{toxinidir}/requirements/test.txt
     -r{toxinidir}/requirements/test-ci.txt
 
-    2.7,pypy,jython: -r{toxinidir}/requirements/test-ci-py2.txt
+    2.7,pypy,jython,cov: -r{toxinidir}/requirements/test-ci-py2.txt
 
     apicheck,linkcheck: -r{toxinidir}/requirements/docs.txt
     flake8,flakeplus: -r{toxinidir}/requirements/pkgutils.txt
 
 commands = pip install -U -r{toxinidir}/requirements/dev.txt
-           py.test -xv --cov=kombu/ --cov-report=xml --no-cov-on-fail
+           py.test -xv
 
 basepython =
-    2.7,flakeplus,flake8,apicheck,linkcheck: python2.7
+    2.7,flakeplus,flake8,apicheck,linkcheck,cov: python2.7
     3.3: python3.3
     3.4: python3.4
     3.5: python3.5
@@ -26,6 +26,9 @@ basepython =
     pypy3: pypy3
     jython: jython
 
+[testenv:cov]
+commands = py.test -xv --cov=kombu --cov-report=xml --no-cov-on-fail
+
 [testenv:apicheck]
 commands = pip install -U -r{toxinidir}/requirements/dev.txt
     sphinx-build -b apicheck -d {envtmpdir}/doctrees docs docs/_build/apicheck