fix bug if we don't do_classifier_free_guidance (#1601)

* fix bug if we don't do_classifier_free_guidance

* update for copied diffusers.pipelines..alt_diffusion..pipeline_alt_diffusion.AltDiffusionPipeline

src/diffusers/pipelines/alt_diffusion/pipeline_alt_diffusion.py

@@ -522,8 +522,8 @@ class AltDiffusionPipeline(DiffusionPipeline):
                     noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
                     noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
 
-                    # compute the previous noisy sample x_t -> x_t-1
-                    latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs).prev_sample
+                # compute the previous noisy sample x_t -> x_t-1
+                latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs).prev_sample
 
                 # call the callback, if provided
                 if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0):

src/diffusers/pipelines/stable_diffusion/pipeline_stable_diffusion.py

@@ -521,8 +521,8 @@ class StableDiffusionPipeline(DiffusionPipeline):
                     noise_pred_uncond, noise_pred_text = noise_pred.chunk(2)
                     noise_pred = noise_pred_uncond + guidance_scale * (noise_pred_text - noise_pred_uncond)
 
-                    # compute the previous noisy sample x_t -> x_t-1
-                    latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs).prev_sample
+                # compute the previous noisy sample x_t -> x_t-1
+                latents = self.scheduler.step(noise_pred, t, latents, **extra_step_kwargs).prev_sample
 
                 # call the callback, if provided
                 if i == len(timesteps) - 1 or ((i + 1) > num_warmup_steps and (i + 1) % self.scheduler.order == 0):