Debugger:It should not hit the breakpoint twice

## Environment data
`dotnet --info` output:

- OS Name: Ubuntu
- OS Version: 14.04
- OS Platform: Linux
- RID: Ubuntu.14.04-x64
- Base Path: /usr/share/dotnet/sdk/1.0.1

OS: LinuxMint 17
VS Code version: v1.11.2
C# Extension version:1.9.0

## Steps to reproduce
1. Execute the following command to create a dotnet project
dotnet new mvc -o web
cd web
dotnet restore
dotnet run
2. Open web project in vscode.
3. Set a breakpoint at line of 2 in Index.cshtml file.
4. Press F5(It hit this bp).
5. Press F5

## Expected behavior
It should in running mode and display UI

## Actual behavior
It hit this breakpoint again.

Log:[log.txt](https://github.com/OmniSharp/omnisharp-vscode/files/950694/log.txt)