fix: QwenImage pipelines silently disable CFG when negative_prompt_embeds mask is None

`encode_prompt()` optimizes all-ones masks to `None`, but `has_neg_prompt`
required both `negative_prompt_embeds` and `negative_prompt_embeds_mask` to
be non-None. This caused CFG to be silently skipped when users passed
pre-computed `negative_prompt_embeds` with an optimized `None` mask.

Remove the `negative_prompt_embeds_mask is not None` check from all 9
QwenImage pipeline variants so that a `None` mask correctly means
"all tokens valid" rather than "no negative prompt".

Fixes #13377

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: Ricardo-M-L

src/diffusers/pipelines/qwenimage/pipeline_qwenimage.py

@@ -585,7 +585,7 @@ def __call__(
         device = self._execution_device
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_controlnet.py

@@ -701,7 +701,7 @@ def __call__(
         device = self._execution_device
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_controlnet_inpaint.py

@@ -740,7 +740,7 @@ def __call__(
         device = self._execution_device
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
         do_true_cfg = true_cfg_scale > 1 and has_neg_prompt
         prompt_embeds, prompt_embeds_mask = self.encode_prompt(

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_edit.py

@@ -706,7 +706,7 @@ def __call__(
             image = image.unsqueeze(2)
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_edit_inpaint.py

@@ -879,7 +879,7 @@ def __call__(
             image = image.to(dtype=torch.float32)
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_edit_plus.py

@@ -694,7 +694,7 @@ def __call__(
                 vae_images.append(self.image_processor.preprocess(img, vae_height, vae_width).unsqueeze(2))
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_img2img.py

@@ -678,7 +678,7 @@ def __call__(
         device = self._execution_device
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_inpaint.py

@@ -823,7 +823,7 @@ def __call__(
         device = self._execution_device
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt:

src/diffusers/pipelines/qwenimage/pipeline_qwenimage_layered.py

@@ -698,7 +698,7 @@ def __call__(
             batch_size = prompt_embeds.shape[0]
 
         has_neg_prompt = negative_prompt is not None or (
-            negative_prompt_embeds is not None and negative_prompt_embeds_mask is not None
+            negative_prompt_embeds is not None
         )
 
         if true_cfg_scale > 1 and not has_neg_prompt: