Retain environment setting of "HOME" for tests that need os.path.expanduser()
to return a readable directory in the build chroot.

--- thefuck-3.25/tests/conftest.py
+++ thefuck-3.25/tests/conftest.py
@@ -64,6 +64,7 @@ def set_shell(monkeypatch):
 
 @pytest.fixture(autouse=True)
 def os_environ(monkeypatch):
-    env = {'PATH': os.environ['PATH']}
+    env = {'PATH': os.environ['PATH'],
+           'HOME': os.environ['HOME']}
     monkeypatch.setattr('os.environ', env)
     return env