Additional test coverage, and upgrade test requirements.

tox.ini

@@ -18,7 +18,7 @@ commands =
     pytest {posargs}
     py36,py37: black --check .
     isort --recursive --check-only --settings-path setup.cfg .
-    flake8 .
+    flake8 borgmatic tests
 
 [testenv:black]
 basepython = python3.7
@@ -32,7 +32,7 @@ commands =
 [testenv:end-to-end]
 deps = -rtest_requirements.txt
 commands =
-    pytest {posargs} tests/end-to-end
+    pytest {posargs} --no-cov tests/end-to-end
 
 [testenv:isort]
 deps = {[testenv]deps}