Tox: Add debug test output

tox.ini

@@ -16,7 +16,7 @@ deps = -r{toxinidir}/requirements/default.txt
        -r{toxinidir}/requirements/test3.txt
        -r{toxinidir}/requirements/test-ci.txt
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
-           nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           C_DEBUG_TEST=1 nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
 
 [testenv:3.3]
 basepython = python3.3
@@ -24,7 +24,7 @@ deps = -r{toxinidir}/requirements/default.txt
        -r{toxinidir}/requirements/test3.txt
        -r{toxinidir}/requirements/test-ci.txt
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
-           nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           C_DEBUG_TEST=1 nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
 
 [testenv:2.7]
 basepython = python2.7
@@ -32,7 +32,7 @@ deps = -r{toxinidir}/requirements/default.txt
        -r{toxinidir}/requirements/test.txt
        -r{toxinidir}/requirements/test-ci.txt
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
-           nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           C_DEBUG_TEST=1 nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
 
 [testenv:2.6]
 basepython = python2.6
@@ -40,7 +40,7 @@ deps = -r{toxinidir}/requirements/default.txt
        -r{toxinidir}/requirements/test.txt
        -r{toxinidir}/requirements/test-ci.txt
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
-           nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           C_DEBUG_TEST=1 nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
 
 [testenv:pypy]
 basepython = pypy
@@ -48,4 +48,4 @@ deps = -r{toxinidir}/requirements/default.txt
        -r{toxinidir}/requirements/test.txt
        -r{toxinidir}/requirements/test-ci.txt
 commands = {toxinidir}/extra/release/removepyc.sh {toxinidir}
-           nosetests -xsv --with-coverage --cover-inclusive --cover-erase []
+           C_DEBUG_TEST=1 nosetests -xsv --with-coverage --cover-inclusive --cover-erase []