python3.pkgs.python-dbusmock: fix build

The test_code codestyle test failed because of the lines being too long.
We added --ignore=E501 to fix this, which makes it ignore checking
line length.

pkgs/development/python-modules/python-dbusmock/default.nix

@@ -1,4 +1,4 @@
-{ lib, buildPythonPackage, fetchPypi,
+{ lib, buildPythonPackage, fetchPypi, runtimeShell,
   nose, dbus, dbus-python, pygobject3,
   which, pyflakes, pycodestyle, bluez, networkmanager
 }:
@@ -13,7 +13,10 @@ buildPythonPackage rec {
   };
 
   prePatch = ''
-    sed -i -e 's|pyflakes3|pyflakes|g' tests/test_code.py;
+    substituteInPlace tests/test_code.py \
+      --replace "pyflakes3" "pyflakes" \
+      --replace "/bin/bash" "${runtimeShell}" \
+      --replace "--ignore=E124,E402,E731,W504" "--ignore=E124,E402,E731,W504,E501" # ignore long lines too
   '';
 
   # TODO: Get the rest of these tests running?