In the dev branch the $PATH is not properly set by config.sh.
In the config.sh.in it should be set to:
export PATH="@MY_PATH@":$PATH
and @MY_PATH@ is set to to output of ${ROOTSYS}/bin
in WriteConfigFile.cmake.
This $ROOTSYS is empty when this module is called.

To Reproduce
Tested on MAC OS and Ubuntu.
Steps to reproduce:

git clone https://github.com/FairRootGroup/FairRoot.git
cd FairRoot && git checkout dev && mkdir build
cd build && cmake ../ && cat config.sh | grep "export PATH"

Expected behavior
The setting of PATH will be printed at the end:
export PATH="/bin":$PATH
The "/bin" should be the path to the FairSoft binary directory.

System information (please complete the following information):

• OS: MacOS 11.6, Ubuntu 2004
• Compiler: clang version 12.0.5, g++ (Ubuntu 9.3.0)
• Environment: FairSoft apr21p1, FairRoot dev