Rename .cs file -> The namespace 'Namespace' already contains a definition for 'ClassName' [netcoreapp1.0]

[jlost]

Environment data

dotnet --info output:

.NET Command Line Tools (1.0.0-preview2-003121)

Product Information:
 Version:            1.0.0-preview2-003121
 Commit SHA-1 hash:  1e9d529bc5

Runtime Environment:
 OS Name:     Windows
 OS Version:  10.0.14393
 OS Platform: Windows
 RID:         win10-x64

VS Code version: 1.5.3
C# Extension version: 1.4.1

Steps to reproduce

1. Open dotnet core solution from base solution directory
2. Open any .cs file
3. Rename it
4. Make a minor, valid change to the code so OmniSharp reevaluates it
5. Observe as errors appear: Class name has The namespace 'Namespace' already contains a definition for 'ClassName' [netcoreapp1.0]. Methods have Type 'ClassName' already defines a member called 'MethodName' with the same parameter types [netcoreapp1.0]

[matthamil]

I had this same issue, see #803.

[gulshan]

Experienced same issue.