test: try to handle loss of testmon data when cancelling test.

Not sure if this works, but I was having an issue where the testmon
database was not being saved properly. When I used ^C to cancel a run,
the next run with --testmon would select no tests even when I changed
files.

The only was to get working again was to delete the .testmon,
.testmon-wal and .testmon-shm files and rerun the whole test suite.
Once the full test suite was run, changing the file would select tests
again.

Author: rouilj

test/conftest.py

@@ -12,3 +12,9 @@ def pytest_configure(config):
     config.addinivalue_line(
         "markers", "pg_schema: tests using schema for postgres"
     )
+
+# try to work around loss of testmon data when ^Cing out of tests.
+def pytest_unconfigure(config):
+    if hasattr(config, "testmon_data"):
+        config.testmon_data.db.con.close()
+