This was just wrong. `devel` might be correct on Fedora but no on Ubuntu :).
@ -271,7 +271,7 @@ if (NOT CATKIN_DEVEL_PREFIX)
# We have a custom error message to tell users how to install python3.
if (NOT PYTHONINTERP_FOUND)
message(FATAL_ERROR "Python 3 not found. Please install Python 3:\n"
" Ubuntu: sudo apt install python3 python3-devel python3-pip\n"
" Ubuntu: sudo apt install python3 python3-dev python3-pip\n"
" macOS: brew install python")
endif()
else()