ropper.py breaks tab completion

[therealdreg]

• [x] Did you use the latest version of GEF from dev branch?
• [x] Is your bug specific to GEF (not GDB)? - Try to reproduce it running gdb -nx
• [x] Did you search through the documentation first?
• [x] Did you check issues (including the closed ones) - and the PR?

Step 1: Describe your environment

Distributor ID: Debian Description: Debian GNU/Linux 10 (buster) Release: 10 Codename: buster

GEF: (Standalone) Blob Hash(/root/.gef-2b72f5d0d9f0f218a91cd1ca5148e45923b950d5.py): 8dc57b700e3c1c85822449033a01c94dfae9e4a6 SHA256(/root/.gef-2b72f5d0d9f0f218a91cd1ca5148e45923b950d5.py): 63d3e10d38a367c3e4d37de8e0701bcdff2a4e7c9a0a4ec5d83ccb8b2fe6188d GDB: 8.2.1 GDB-Python: 3.7

Step 2: Describe your problem

ropper.py breaks tab completion

Steps to reproduce

1. open gdb /bin/ls
2. write sta + TAB

solved #73