Fix for appveyor

Author: henryiii

.appveyor.yml

@@ -61,6 +61,7 @@ build_script:
     -DPYBIND11_WERROR=ON
     -DDOWNLOAD_CATCH=ON
     -DCMAKE_SUPPRESS_REGENERATION=1
+    .
 - set MSBuildLogger="C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
 - cmake --build . --config %CONFIG% --target pytest -- /m /v:m /logger:%MSBuildLogger%
 - cmake --build . --config %CONFIG% --target cpptest -- /m /v:m /logger:%MSBuildLogger%