"Dirty" suffix when making a new package

[EranMani]

I have an issue when making a package. I always get the suffix "dirty", or a series of numbers and letters. It creates an issue because the client API version is different from the simulator API.
This is the message I get from the CMD:

WARNING: Version mismatch detected: You are trying to connect to a simulator that might be incompatible with this API
WARNING: Client API version = 0.9.12
WARNING: Simulator API version = 0.9.12-1-gbbd4g96-dirty
WARNING: You are currently in asynchronous mode and could experience some issues with the traffic simulation
INFO: streaming client: failed to read data: the file handle supplied is not valid

What does "dirty" mean?
what is causing this issue? is it because I'm uploading custom assets into Carla?
How I can fix this "dirty" so it wont create any future issues between the client and the simulator connection?