Debugging causes "More than one build script specified" error if a space exists in the file path

If I try to debug a cake file in Visual Studio Code that contains a space in the directory name then I always get a "More than one build script specified" error. This doesn't occur if there are no spaces in the directory name.

I'm using the standard launch.json file specified below:

```
{
// Use IntelliSense to learn about possible attributes.
// Hover to view descriptions of existing attributes.
// For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
"version": "0.2.0",
"configurations": [

{
"name": "Cake: Debug Script (CoreCLR)",
"type": "coreclr",
"request": "launch",
"program": "${workspaceRoot}/tools/Cake.CoreCLR/Cake.dll",
"args": [
"${workspaceRoot}/build.cake",
"--debug",
"--verbosity=diagnostic"
],
"cwd": "${workspaceRoot}",
"stopAtEntry": true,
"externalConsole": false
}
]
}
```

The output when I debug a build.cake file in the directory "D:\Temp\Cake Test" is as follows:

```
-------------------------------------------------------------------
You may only use the Microsoft .NET Core Debugger (vsdbg) with
Visual Studio Code, Visual Studio or Visual Studio for Mac software
to help you develop and test your applications.
-------------------------------------------------------------------
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Private.CoreLib.ni.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\Cake.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Runtime.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\mscorlib.dll'. Cannot find or open the PDB file.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\Cake.Core.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Linq.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\Cake.Common.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\Autofac.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\Cake.NuGet.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Runtime.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.IO.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Collections.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.ComponentModel.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Console.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Threading.Tasks.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Reflection.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Globalization.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Threading.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Collections.Concurrent.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Linq.Expressions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Reflection.TypeExtensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Reflection.Emit.ILGeneration.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Reflection.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.Reflection.Emit.Lightweight.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'Anonymously Hosted DynamicMethods Assembly'.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Reflection.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.ObjectModel.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Runtime.InteropServices.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\System.IO.FileSystem.Primitives.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Text.Encoding.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.Text.Encoding.Extensions.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
More than one build script specified.
Loaded 'D:\Temp\Cake Test\tools\Cake.CoreCLR\runtimes\win\lib\netstandard1.1\System.Runtime.InteropServices.RuntimeInformation.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.
Loaded 'C:\Program Files\dotnet\shared\Microsoft.NETCore.App\1.0.9\System.IO.FileSystem.dll'. Skipped loading symbols. Module is optimized and the debugger option 'Just My Code' is enabled.

Usage: Cake.exe [script] [--verbosity=value]
[--showdescription] [--dryrun] [..]

Example: Cake.exe
Example: Cake.exe build.cake --verbosity=quiet
Example: Cake.exe build.cake --showdescription

Options:
--verbosity=value Specifies the amount of information to be displayed.
(Quiet, Minimal, Normal, Verbose, Diagnostic)
--debug Performs a debug.
--showdescription Shows description about tasks.
--dryrun Performs a dry run.
--version Displays version information.
--help Displays usage information.

The program '[18032] Cake.dll' has exited with code 1 (0x1).

```

Start by reproducing the VS Code CoreCLR launch configuration from launch.json with the workspace at D:\Temp\Cake Test and the build.cake argument. Trace how the extension invokes Cake.dll and handles the workspace path; done means debugging succeeds when the directory path contains spaces without reporting multiple build scripts.

Written by the indexing model from the issue text.