Multiple local imports

Hello!

I have a very, I think, specific issue and I would like to know, why PyCall does that and how to fix it.

Let's assume, that I have 2 folders `folder1` and `folder2` which are repositories written in python and each has a main script file `main1.py` and `main2.py`, and those two just have inside them multiple local imports and a function `main`.

Then I have two julia scripts `folder1.jl` and `folder2.jl`, which call those `main` functions from those two folders. The code for `folder1.jl` goes like this:

```julia
pushfirst!(PyVector(pyimport("sys")."path"), folder1)
execute_JL = pyimport("main1")
pyimport("importlib").reload(execute_JL)[:main](args)
```


And both julia scripts work fine. Now I want to combine them and call both scripts in the third script `combine.jl`.

This no longer works and here are two things that happen.

1. If the first element of `PyVector(pyimport("sys")."path")` is `folder1`, then I can import `main1`, if it's `folder2`, then no. But that I managed to fix this by just removing the folder from the path, once I ran the script.
2. If I do `pyimport("main1")`, I then cannot do `pyimport("main2")` and the opposite.

In both of these cases the first time you run the code the error doesn't even say anything - just that `PyObject(Ptr{PyCall.PyObject_struct} @0x00000000521c49f0), PyObject(Ptr{PyCall.PyObject_struct} @0x00000000650bf2e8), PyObject(Ptr{PyCall.PyObject_struct} @0x00000000650b58c8))`, for example. The second time you run it - all the local imports in the file that cannot be imported fail.

Can someone tell me why that happens?

P.S. As a workaround, I could probably create `setup.py` files in those folders and install them like python libraries, but I still wonder why right now I can't make this work.

首先使用 main1.py 和 main2.py 重现从 folder1.jl、folder2.jl 和 combine.jl 导入的过程，然后检查第一次导入后 Python 的 sys.path 和模块状态。完成的标准是确定为什么两个本地导入树无法通过 PyCall 共存，并记录或验证一个可行的修复方案。

由索引模型根据 Issue 内容生成。