CMake fails with custom cmake modules OpenSSL

[AndreReinhold]

Describe the bug
CMake fails with paho.mqttp.cpp 1.5.0 in my project because I am using a custom project based OpenSSL library for an embedded software that is found via a custom FindOpenSSL.cmake in my top level subdirectory cmake/modules/FindOpenSSL.cmake.

To Reproduce
With commit 9a4fd08 the CMAKE_MODULE_PATH gets overwritten by
set(CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")

So my top-level modification of CMAKE_MODULE_PATH is getting overwritten that I set with
list(APPEND CMAKE_MODULE_PATH "${PROJECT_SOURCE_DIR}/cmake/modules")

Expected behavior
CMakeLists.txt should not set CMAKE_MODULE_PATH, but only append.

Log files
CMake Error at C:/software/CMake/share/cmake-3.24/Modules/FindPackageHandleStandardArgs.cmake:230 (message):
Could NOT find OpenSSL, try to set the path to OpenSSL root folder in the
Call Stack (most recent call first):
C:/software/CMake/share/cmake-3.24/Modules/FindPackageHandleStandardArgs.cmake:594 (_FPHSA_FAILURE_MESSAGE)
C:/software/CMake/share/cmake-3.24/Modules/FindOpenSSL.cmake:599 (find_package_handle_standard_args)
3rdParty/paho.mqtt.cpp/externals/paho-mqtt-c/src/CMakeLists.txt:238 (find_package)

[icraggs]

@fpagliughi - have you seen this?