Steps to repro:

1. Check out https://github.com/microsoft/visualfsharp
2. Open FSharp.sln using MonoDevelop.
3. Rename any project.
4. In repo, do git status
5. Observe that there are a bunch of updates similar to the following:

-Project("{F2A71F9B-5D33-465A-A702-920D77279786}") = "FSharp.Tests.FSharpSuite", "tests\fsharp\FSharp.Tests.FSharpSuite.fsproj", "{C163E892-5BF7-4B59-AA99-B0E8079C67C4}"
+Project("{f2a71f9b-5d33-465a-a702-920d77279786}") = "FSharp.Tests.FSharpSuite", "tests\fsharp\FSharp.Tests.FSharpSuite.fsproj", "{C163E892-5BF7-4B59-AA99-B0E8079C67C4}"

Note that F2A71F9B-5D33-465A-A702-920D77279786 gets changed to f2a71f9b-5d33-465a-a702-920d77279786.

I believe that MonoDevelop should not change the casing of these GUIDs.

VS bug #686313