Minimal test case:
mkdir test && cd test && mkdir subtest && echo "a = 0" > subtest/config.py && echo "from config import a" > subtest/test.py
Running bpython -i subtest/test.py should yield an interpreter with variable a=0. However, it yields
Traceback (most recent call last):
File "subtest/test.py", line 1, in
from config import a
ImportError: No module named config
Running bpython subtest/test.py gives the expected result (no errors), python -i subtest/test.py also gives the expected result (a shell with variable a=0)