angr loader object keeps open files after a .close()

[jsaunders-kbr]

With the following series of operations:
loader = cle.Loader(file)
...
loader.close()

Cle will keep the file open internally until python closes, making it impossible to among other things, os.remove() to delete the file on Windows due to the file being held open.

While I've only been able to have this bug occur on cle 8.19.2.4 (newer versions explode spectacularly due to issues with psutil on my system), I was told on the angr slack to report it anyway as it's a known issue that needs to be tracked.

[ltfish]

Thank you for reporting it!

[rhelmot]

I can't reproduce this on linux (cpython >3.5 will give you a warning if you have any unclosed file handles on process exit), so this will need to be debugged on windows.