cd into dir with python tests.

Python interpreter can't find otherwise if called from external directory (e.g.
in vpath build).

Author: arssher

tests/python/Makefile

@@ -1,2 +1,6 @@
+# we need to cd into dir with tests.py, otherwise unittest won't find it
+# dir containing this makefile
+mkfile_dir := $(shell dirname $(shell readlink -f $(abspath $(lastword $(MAKEFILE_LIST)))))
+
 all:
-	python3 -m unittest tests.py -v -f
+	cd $(mkfile_dir) && python3 -m unittest tests.py -v -f