wm.py needs import os in some of its execute funcs + now we can have blender2.60x version :)

I guess someone did a cleanup in the file and forgot to test "add an Add-On" ;)
+ a bug I found while studying the cmake files

build_files/cmake/macros.cmake

@@ -482,7 +482,7 @@ macro(get_blender_version)
 	if(${_out_version_char_empty})
 		set(BLENDER_VERSION_CHAR_INDEX "0")
 	else()
-		set(_char_ls a b c d e f g h i j k l m n o p q r s t u v w q y z)
+		set(_char_ls a b c d e f g h i j k l m n o p q r s t u v w x y z)
 		list(FIND _char_ls ${BLENDER_VERSION_CHAR} _out_version_char_index)
 		math(EXPR BLENDER_VERSION_CHAR_INDEX "${_out_version_char_index} + 1")
 		unset(_char_ls)

release/scripts/startup/bl_operators/wm.py

@@ -1683,6 +1683,7 @@ class WM_OT_addon_install(Operator):
 
     @staticmethod
     def _module_remove(path_addons, module):
+        import os
         module = os.path.splitext(module)[0]
         for f in os.listdir(path_addons):
             f_base = os.path.splitext(f)[0]
@@ -1699,6 +1700,7 @@ class WM_OT_addon_install(Operator):
         import traceback
         import zipfile
         import shutil
+        import os
 
         pyfile = self.filepath