controlnet union XL, make control_image immutible

when this argument is passed a list, __call__
modifies its content, since it is pass by reference
the list passed by the caller gets its content
modified unexpectedly

make a copy at method intro so this does not happen

Author: Teriks

src/diffusers/pipelines/controlnet/pipeline_controlnet_union_inpaint_sd_xl.py

@@ -1370,6 +1370,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]

src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl.py

@@ -1160,6 +1160,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]

src/diffusers/pipelines/controlnet/pipeline_controlnet_union_sd_xl_img2img.py

@@ -1306,6 +1306,8 @@ def __call__(
 
         if not isinstance(control_image, list):
             control_image = [control_image]
+        else:
+            control_image = control_image.copy()
 
         if not isinstance(control_mode, list):
             control_mode = [control_mode]