Debugger: The 'debug test' is not disabled in debugging

[GraceDong]

Environment data

dotnet --info output:
Product Information:
Version: 1.0.1
Commit SHA-1 hash: 005db40cd1
Runtime Environment:
OS Name: Ubuntu
OS Version: 16.10
OS Platform: Linux
RID: Ubuntu.16.10-x64
Base Path: /usr/share/dotnet/sdk/1.0.1

VS Code version: v1.11.2
C# Extension version: v.1.9.0

Steps to reproduce

1. Open attached folder with VSCode;
   test_xunit.zip
2. Set a breakpoint at the line of 11 in UnitTest1.cs;
3. Debug test and wait for break mode;

Expected behavior

The debug test should be disabled.

Actual behavior

The debug test is not disabled. And when I click debug test again, pop an error message as following:

Investigation

1. In VS, Run Tests, Debug Tests and Restart was be disabled if the project is being debugged.
2. In VSCode, click Run Tests after step Allow terminal configuration on Linux (currently hard-coded to gnome-terminal). #3, .NET Test Log as following:
   
3. In VSCode, click Restart after step Allow terminal configuration on Linux (currently hard-coded to gnome-terminal). #3, the project run to end. Could you please help me to confirm if it is expected? OmniSharp Log as following:
   
4. If debug test can not be disabled, can you improve the prompt? E.g: Failed to start debugger: Is being used by another process.

[DustinCampbell]

I have a change to fix this, but it's fairly large. I'm going to hold this fix until 1.11.