Not set paths when LIBPYTHON is specified

Author: rmatsumiya

lib/pycall/libpython/finder.rb

@@ -40,10 +40,6 @@ def find_libpython(python = nil)
           debug_report("find_libpython(#{python.inspect})")
           python, python_config = find_python_config(python)
 
-          set_PYTHONHOME(python_config)
-          libs = make_libs(python_config)
-          libpaths = make_libpaths(python_config)
-
           # Try LIBPYTHON environment variable first.
           if (libpython = ENV['LIBPYTHON'])
             if File.file?(libpython)
@@ -59,6 +55,9 @@ def find_libpython(python = nil)
           end
 
           # Find libpython (we hope):
+          set_PYTHONHOME(python_config)
+          libs = make_libs(python_config)
+          libpaths = make_libpaths(python_config)
           multiarch = python_config[:MULTIARCH] || python_config[:multiarch]
           libs.each do |lib|
             libpaths.each do |libpath|