CLN: cleanup tox.ini, remove stale pandas/setup.py, fix tox warning

tox.ini

@@ -7,18 +7,36 @@
 envlist = py25, py26, py27, py31, py32
 
 [testenv]
-commands =
-    {envpython} setup.py clean build_ext install
-    {envbindir}/nosetests tests
-    /bin/rm -rf {toxinidir}/build {toxinidir}/tests
 deps =
     cython
     numpy >= 1.6.1
     nose
     pytz
 
+# cd to anything but the default {toxinidir} which
+# contains the pandas subdirectory and confuses
+# nose away from the fresh install in site-packages
+changedir = {envdir}
+
+commands =
+    # TODO:  --exe because of GH #761
+    {envbindir}/nosetests --exe pandas.tests
+    # cleanup the temp. build dir created by the tox build
+    /bin/rm -rf {toxinidir}/build
+
+    # quietly rollback the install.
+    # Note this line will only be reached if the tests
+    # previous lines succeed (in particular, the tests),
+    # but an uninstall is really only required when
+    # files are removed from source tree, in which case,
+    # stale versions of files will will remain in the venv,
+    # until the next time uninstall is run.
+    #
+    # tox should provide a preinstall-commands hook.
+    pip uninstall pandas -qy
+
+
 [testenv:py25]
-changedir = .tox/py25/lib/python2.5/site-packages/pandas
 deps =
     cython
     numpy >= 1.6.1
@@ -27,13 +45,9 @@ deps =
     simplejson
 
 [testenv:py26]
-changedir = .tox/py26/lib/python2.6/site-packages/pandas
 
 [testenv:py27]
-changedir = .tox/py27/lib/python2.7/site-packages/pandas
 
 [testenv:py31]
-changedir = .tox/py31/lib/python3.1/site-packages/pandas
 
 [testenv:py32]
-changedir = .tox/py32/lib/python3.2/site-packages/pandas