Using Android Studio and Eclipse in the same git repo.
The the gitignore is not enough to solve this problems.
This is my solution.
(In this case most user use eclipse.)
First, create eclipse repo. Pull git repo and import to Android Studio.
Run script that will every copy files from Android Studio and map with the eclipse folder structure. Every time we build the Android project by add the external tools when build(Android Studio). Before we pull anything from git (to eclipse) you need to run script to copy all files to eclipse then pull. After pull you must run the script the copy every files from eclipse to Android Studio.
See how to implement that script here