More "relpath" try/except protection...

Note: import gimp image also would need it, but it would anyway need a good cleanup (handling of paths is ugly), so did not bothered with it for now.

io_import_images_as_planes.py

@@ -453,15 +453,10 @@ class IMPORT_OT_image_to_plane(Operator, AddObjectHelper):
         image.use_fields = self.use_fields
 
         if self.relative:
-            # can't always find the relative path
-            # (between drive letters on windows)
-            try:
-                filepath_rel = bpy.path.relpath(image.filepath)
+            try:  # can't always find the relative path (between drive letters on windows)
+                image.filepath = bpy.path.relpath(image.filepath)
             except ValueError:
-                filepath_rel = None
-
-            if filepath_rel is not None:
-                image.filepath = filepath_rel
+                pass
 
     def set_texture_options(self, context, texture):
         texture.image.use_alpha = self.use_transparency

texture_paint_layer_manager.py

@@ -559,12 +559,16 @@ def save_painted(ts):
                         name = name +'.tga' 
                         
                     bpy.context.scene.render.image_settings.color_mode = 'RGBA'                          
-                    fp =bpy.path.abspath('//textures' + sep + name)
+                    fp = bpy.path.abspath('//textures' + sep + name)
                     try:
                         i.save_render(fp)
                         i.source = 'FILE'
                         if bpy.context.user_preferences.filepaths.use_relative_paths:
-                            i.filepath = bpy.path.relpath(fp) 
+                            # can't always find the relative path (between drive letters on windows)
+                            try:
+                                i.filepath = bpy.path.relpath(fp)
+                            except ValueError:
+                                i.filepath = fp
                         else:
                             i.filepath = fp
                         i.name = name