Single header directory causes incorrect 'showSourceSubFolders' behavior (simple reproducible project attached)

# file structure
Test/
├── CMakeLists.txt
├── main.c
└── inc1/
    └── a.h

# project view
Test/
├── a.h  <- no header dir !!
└── main.c

# file structure
Test/
├── CMakeLists.txt
├── main.c
├── inc1/
│   └── a.h
└── inc2/
    └── b.h

# project view
Test/
├── main.c
├── inc1/
│   └── a.h
└── inc2/
    └── b.h

#!/bin/sh

function _gen_fake_files()
{
    mkdir -p inc1 inc2
    : > main.c
    : > inc1/a.h
    : > inc2/b.h
}

function _gen_cmake_file()
{
    cat > CMakeLists.txt << EOF
cmake_minimum_required(VERSION 2.8)

project(Test)

add_executable(Test
    main.c
    inc1/a.h
    inc2/b.h  # comment out this line to reproduce the bug
)

target_include_directories(Test PRIVATE
    \${CMAKE_CURRENT_SOURCE_DIR}
)

EOF
}

_gen_fake_files
_gen_cmake_file