Issue title: Problems with CopySources
 Issue body: I have big solution with many projects and files.
I turned on Copy Sources function. But it works in absolutely unexpected manner.
In some projects it copies files correctly, in some projects - not.

For example:
I have RemoteBuildProjectDirectory: **$(RemoteRootDir)DEV8/Mod/$(ProjectName)**,
ProjectName: PiLib
I have source file: **S:\DEV8\Mod\PiLib\Pi\PiStringUtils.cpp**.
I expect it to be copied to **~/Dev/P7/DEV8/Mod/PiLib/Pi/PiStringUtils.cpp**. 
But instead I get: **~/Dev/P7/DEV8/Mod/PiLib/Mod/PiLib/Pi/PiStringUtils.cpp**
If I change RemoteBuildProjectDirectory: **$(RemoteRootDir)DEV8/Mod/**, I get **~/Dev/P7/DEV8/Mod/Pi/PiStringUtils.cpp**.

What should I do to correctly copy files?

I use VS2015 Update 3, VSLinux 1.0.6, Ubuntu 14.04 x64


 Comments: 
 Comment 0: Could you tell what your project directory is set to, locally? This is the folder, on Windows, where the .vcxproj file is
 Comment 1: No, project path is S:\DEV8\Mod\PiLib\PiLib.vcxproj
And so for other projects: each .vcxproj file is in it's own subdirectory under S:\DEV8\Mod
Some projects are under S:\DEV8\WSF directory (each project in it's own subdirectory)
Solution file is in root directory S:\DEV8
 Comment 2: Hi, guys!

What should we do to get this error fixed?
In VS2017 RTM we have the old same problem: remote copying doesn't work as we expect.
 Comment 3: Closing as no activity since more than 1 year. Feel free to reopen it if you believe it is useful to keep track of it, thanks.
{'source': 'GithubIssues', 'repo_name_with_owner': 'Microsoft/VSLinux', 'issue_id': 197568286, 'repo_stars': 206.0}