Don't use requirements for now, and use the git version instead in tox

tox.ini

@@ -8,7 +8,9 @@ deps =
     docopt
 # coloroma for colored debug output
     colorama
-    -rrequirements.txt
+# Overwrite the parso version (only used sometimes).
+    git+https://github.com/davidhalter/parso.git
+#    -rrequirements.txt
 passenv = JEDI_TEST_ENVIRONMENT
 setenv =
 # https://github.com/tomchristie/django-rest-framework/issues/1957
@@ -23,8 +25,6 @@ setenv =
     env36: JEDI_TEST_ENVIRONMENT=36
     env37: JEDI_TEST_ENVIRONMENT=37
 commands =
-# Overwrite the parso version (only used sometimes).
-    pip install git+https://github.com/davidhalter/parso.git
     py.test {posargs:jedi test}
 [testenv:py27]
 deps =