[tmp] #8

.circleci/config.yml

@@ -146,7 +146,7 @@ jobs:
       - restore_cache:
           keys:
               - tox-cache-ddtracerun-{{ checksum "tox.ini" }}
-      - run: tox -e '{py27,py34,py35,py36}-ddtracerun' --result-json /tmp/ddtracerun.results
+      - run: TOX_SKIP_DIST=False; tox --recreate -e '{py27,py34,py35,py36}-ddtracerun' --result-json /tmp/ddtracerun.results
       - persist_to_workspace:
           root: /tmp
           paths:

tox.ini

@@ -16,7 +16,7 @@
 ##
 #See related github topic:
 # - https://github.com/pypa/virtualenv/issues/596
-skipsdist=True
+skipsdist={env:TOX_SKIP_DIST:True}
 envlist =
     flake8
     wait
@@ -91,6 +91,10 @@ basepython =
 
 deps =
     wrapt
+# In this version of tox (2.91) negations seems not to be working, and in fact they are not mentioned in the doc for
+# 2.9.1 (https://tox.readthedocs.io/en/2.9.1/config.html#factors-and-factor-conditional-settings). If we update to
+# to version 3.x we can use negations and install msgpack-python only when we are not installing specific version of the
+# library, e.g. something like: !msgpack: msgpack-python
     msgpack-python
     pytest
     opentracing