Using environment variables in var_files in sceptre 2.4

[tsarpi1]

In sceptre 1.3.4 I could have

config.yaml file with

user_variables:
branch: {{ environment_variable.BRANCH_NAME }

When I try the same in scepte2.4
in a var_file (below config/d-app-01/config.yaml ) I get

(sceptre24) $ sceptre --var-file config/config.yaml --var-file config/d-app-01/config.yaml validate d-app-01 sceptre24
Traceback (most recent call last):
File "/home/tsarpi/.venv/sceptre24/bin/sceptre", line 8, in
sys.exit(cli())
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/core.py", line 829, in call
return self.main(*args, **kwargs)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/core.py", line 782, in main
rv = self.invoke(ctx)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/core.py", line 1256, in invoke
Command.invoke(self, ctx)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/core.py", line 1066, in invoke
return ctx.invoke(self.callback, **ctx.params)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/core.py", line 610, in invoke
return callback(*args, **kwargs)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/click/decorators.py", line 21, in new_func
return f(get_current_context(), *args, **kwargs)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/sceptre/cli/helpers.py", line 36, in decorated
return func(*args, **kwargs)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/sceptre/cli/init.py", line 70, in cli
parsed = yaml.safe_load(fh.read())
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/init.py", line 162, in safe_load
return load(stream, SafeLoader)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/init.py", line 114, in load
return loader.get_single_data()
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/constructor.py", line 51, in get_single_data
return self.construct_document(node)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/constructor.py", line 60, in construct_document
for dummy in generator:
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/constructor.py", line 413, in construct_yaml_map
value = self.construct_mapping(node)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/constructor.py", line 218, in construct_mapping
return super().construct_mapping(node, deep=deep)
File "/home/tsarpi/.venv/sceptre24/lib/python3.6/site-packages/yaml/constructor.py", line 142, in construct_mapping
"found unhashable key", key_node.start_mark)
yaml.constructor.ConstructorError: while constructing a mapping
in "", line 18, column 9:
branch: {{ environment_variable.BRANCH_N ...
^
found unhashable key
in "", line 18, column 10:
branch: {{ environment_variable.BRANCH_NA ...

I can use it with no problems in a stack config files.