Update to newest MSBuild plugin breaks passing of release configurations with spaces in them

The fix from #17876 breaks my builds which are using parameters with spaces, f.i.

Path To MSBuild.exe: c:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe
15:28:23 Executing the command cmd.exe /C c:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe "/p:Configuration="Release Wcdma"" /p:Platform=x86 /p:CheckIn=true /p:CheckOut=true /p:Crypt=true /t:rebuild C:\Snapshots\RS-CONTEST-RF-WCDMA_2.4x\contest_sw\Conformance.sln && exit %%ERRORLEVEL%% from C:\Snapshots\RS-CONTEST-RF-WCDMA_2.4x
15:28:23 [RS-CONTEST-RF-WCDMA_2.4x] $ cmd.exe /C c:\Windows\Microsoft.NET\Framework\v4.0.30319\MSBuild.exe '/p:Configuration="Release Wcdma"' /p:Platform=x86 /p:CheckIn=true /p:CheckOut=true /p:Crypt=true /t:rebuild C:\Snapshots\RS-CONTEST-RF-WCDMA_2.4x\contest_sw\Conformance.sln && exit %%ERRORLEVEL%%
15:28:23 Microsoft (R) Build Engine Version 4.0.30319.1
15:28:23 [Microsoft .NET Framework, Version 4.0.30319.296]
15:28:23 Copyright (C) Microsoft Corporation 2007. All rights reserved.
15:28:23
15:28:23 MSBUILD : error MSB1008: Only one project can be specified.
15:28:23 Switch: C:\Snapshots\RS-CONTEST-RF-WCDMA_2.4x\contest_sw\Conformance.sln

Note the parameter "/p:Configuration="Release Wcdma"" which was '/p:Configuration="Release Wcdma"' in the GUI. Without the single quotes (/p:Configuration="Release Wcdma") the result is the same...

Downgrading to the previous version of the msbuild plugin fixes the problem.