fix: tests: Test state file consistency

Test that two different instances of state don't overwrite each other.
This test don't past in this commit, will pass in the next bugfix.

Bugfix v0.7.0, which claimed 100% test coverage on state.

tests/unit/util/test_state.py

@@ -117,3 +117,12 @@ def test_state_iter(tmpdir):
     for key in d:
         state[key] = d[key]
     assert set([key for key in state]) == set(d)
+
+
+def test_two_instances(tmpdir):
+    """Test that 2 different intances don't overwrite each other"""
+    s1 = State(os.path.join(str(tmpdir), 'state.dat'))
+    s2 = State(os.path.join(str(tmpdir), 'state.dat'))
+    s1["x"] = "foo"
+    s2["y"] = "bar"
+    assert s2["x"] == "foo"