Fixed bug where a symlinked project path caused an issue

Blender would report that the blend file wasn't in the project path, even
though it was. This was caused by resolving symlinks in the project path,
but not in the blendfile path.

blender_cloud/flamenco/__init__.py

@@ -477,7 +477,13 @@ def _render_output_path(
         return None
 
     try:
-        proj_rel = blend_filepath.parent.relative_to(project_path)
+        blend_abspath = blend_filepath.resolve().absolute()
+    except FileNotFoundError:
+        # Path.resolve() will raise a FileNotFoundError if the path doesn't exist.
+        return None
+
+    try:
+        proj_rel = blend_abspath.parent.relative_to(project_path)
     except ValueError:
         return None