Improve Transformers backend model loading QoL (#17039)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

Author: hmellor

vllm/model_executor/model_loader/utils.py

@@ -55,7 +55,10 @@ def resolve_transformers_arch(model_config: ModelConfig,
         #     "AutoModelFor<Task>": "<your-repo-name>--<config-name>",
         # },
         auto_modules = {
-            name: get_class_from_dynamic_module(module, model_config.model)
+            name:
+            get_class_from_dynamic_module(module,
+                                          model_config.model,
+                                          revision=model_config.revision)
             for name, module in sorted(auto_map.items(), key=lambda x: x[0])
         }
         custom_model_module = auto_modules.get("AutoModel")
@@ -97,10 +100,10 @@ def get_model_architecture(
         architectures = ["QuantMixtralForCausalLM"]
 
     vllm_supported_archs = ModelRegistry.get_supported_archs()
-    is_vllm_supported = any(arch in vllm_supported_archs
-                            for arch in architectures)
-    if (not is_vllm_supported
-            or model_config.model_impl == ModelImpl.TRANSFORMERS):
+    vllm_not_supported = not any(arch in vllm_supported_archs
+                                 for arch in architectures)
+    if (model_config.model_impl == ModelImpl.TRANSFORMERS or
+            model_config.model_impl != ModelImpl.VLLM and vllm_not_supported):
         architectures = resolve_transformers_arch(model_config, architectures)
 
     model_cls, arch = ModelRegistry.resolve_model_cls(architectures)