Fix relative path problem

tfw/internals/ref_counter/test_ref_counter.py

@@ -1,8 +1,8 @@
 # pylint: disable=redefined-outer-name
 from dataclasses import dataclass
 from textwrap import dedent
-from os import mkfifo
-from os.path import join
+from os import chdir, mkfifo
+from os.path import dirname, join, realpath
 from signal import SIGINT
 from subprocess import DEVNULL, Popen, PIPE
 from tempfile import TemporaryDirectory
@@ -35,6 +35,7 @@ class CounterContext:
 @pytest.fixture
 def context():
     with TemporaryDirectory() as workdir:
+        chdir(dirname(realpath(__file__)))
         pipepath = join(workdir, 'test.pipe')
         mkfifo(pipepath)
         yield CounterContext(join(workdir, 'test.lock'), pipepath)