It spent me several hours to find out the root cause why the importing operation failed while importing ‘a.b.c’ module.

I wrote a function in init.py in ‘a’ package, I plan to get current module path use:

self.cur_dir = __path__.pop()

In later logic, if I tried to load some module under this ‘a’ package, it always failed with below error:

ImportError: No module named b.c

But it is fine when I try to load it via python shell or by other ways. Finally, I found the problem comes from this point: __path__.pop()`, it pops and remove `__path__` info from global namespace, and next `__import__` function still parse the real module which need to load as 'b.c', but now it cannot find the `__path__ information, so it don’t know where to load ‘b.c’ module, which in turn report ‘No module named …’ error. Sigh! Never do any modify/write operation to global stuff unless you are very sure about it.