What version are you running?
1.0.1

What steps will reproduce the problem?

rbt list-repo-types


What is the expected output? What do you see instead?

What operating system are you using?
Debian
Attach the debug out from the command.

$ rbt list-repo-types --debug
>>> RBTools 1.0.1
>>> Python 2.7.15 (default, Sep  9 2018, 23:56:39) 
[GCC 4.9.2]
>>> Running on Linux-4.14.16-grsec-kapsi-x86_64-with-debian-8.11
>>> Home = [..]
>>> Current directory = [..]
>>> Command line: rbt list-repo-types --debug
The following repository types are supported by this installation
of RBTools. Each "<type>" may be used as a value for the
"--repository-type=<type>" command line argument. Repository types
which are detected in the current directory are marked with a "*"
[*] "<type>": <Name>
>>> Running: tf vc help



Please provide any additional information below.
System has command 'tf' but it is not for Team Foundation Server.

tf (1)               - TinyFugue, a MUD client

rbt gets stuck when executing tf vc help because tf waits for user's input.