Correctly honor PIP_INSTALL_PREFIX on Debian-based distributions

Author: gergondet

CMakeLists.txt

@@ -107,7 +107,11 @@ macro(ADD_BINDINGS PYTHON PYTHON_EXECUTABLE SOURCES)
     if(DEFINED PIP_INSTALL_PREFIX)
       _pip_has_install_system(${PYTHON_EXECUTABLE} PIP_HAS_INSTALL_SYSTEM)
       execute_process(COMMAND ${PYTHON_EXECUTABLE} -c "import sys; print(\"python{}.{}\".format(sys.version_info.major, sys.version_info.minor));" OUTPUT_VARIABLE PYTHON_VERSION OUTPUT_STRIP_TRAILING_WHITESPACE)
-      set(PIP_TARGET "${PIP_INSTALL_PREFIX}/lib/${PYTHON_VERSION}/site-packages/")
+      if(EXISTS /etc/debian_version)
+        set(PIP_TARGET "${PIP_INSTALL_PREFIX}/lib/${PYTHON_VERSION}/dist-packages/")
+      else()
+        set(PIP_TARGET "${PIP_INSTALL_PREFIX}/lib/${PYTHON_VERSION}/site-packages/")
+      endif()
       set(PIP_EXTRA_OPTIONS --target "${PIP_TARGET}")
       if(${PIP_HAS_INSTALL_SYSTEM})
         set(PIP_EXTRA_OPTIONS --system ${PIP_EXTRA_OPTIONS})