pytest: -v and default XDISTN to 1 (#4481)

tox.ini

@@ -8,7 +8,7 @@ envlist = py{35,36,37},flake8
 deps =
      -rrequirements.d/development.txt
      -rrequirements.d/fuse.txt
-commands = py.test -n {env:XDISTN:4} -rs --cov=borg --cov-config=.coveragerc --benchmark-skip --pyargs {posargs:borg.testsuite}
+commands = py.test -v -n {env:XDISTN:1} -rs --cov=borg --cov-config=.coveragerc --benchmark-skip --pyargs {posargs:borg.testsuite}
 # fakeroot -u needs some env vars:
 passenv = *