Multiple MAP_IMPORTED_CONFIG_ values breaks Visual Studio projects
After upgrading to CMake 3.9, the subprojects built with ExternalProject_Add are failing with:
C:\Program Files (x86)\MSBuild\Microsoft.Cpp\v4.0\Microsoft.CppCommon.targets(21,33): error MSB4115: The "HasTrailingSlash" function only accepts a scalar value, but its argument "$(IntDir)" evaluates to "x64\RelWithDebInfo;Release\" which is not a scalar
This affects CMake 3.9.0 and 3.9.1. We have not tried 3.9.2.