fix: dict.update instead of | operator

* allows for python@:3.8 compatibility

Change-Id: Id24d73dc4c9574852cf1edc2c99d9a56da1fbb4f

bin/yashchiki

@@ -152,7 +152,8 @@ tmpdir.mkdir(exist_ok=True, parents=True)
 
 # collection of environment variables used to configure the shell scripts'
 # behavior
-env = {
+env = os.environ.copy()
+env.update({
     "DOCKER_BASE_IMAGE": config["docker_base_image"],
     # This needs to be here because otherwise the default python
     # (2.7.18) will pollute the spec and lead to a conflict
@@ -174,10 +175,10 @@ env = {
     "TMPDIR": tmpdir,
     "YASHCHIKI_CACHES_ROOT": args.caches_dir,
     "YASHCHIKI_JOBS": str(args.jobs),
-} | os.environ
+})
 
 if args.build_cache_on_failure_name:
-    env = env | {"YASHCHIKI_BUILD_CACHE_ON_FAILURE_NAME": args.build_cache_on_failure_name}
+    env.update({"YASHCHIKI_BUILD_CACHE_ON_FAILURE_NAME": args.build_cache_on_failure_name})
 
 # create directory for logs
 args.log_dir.mkdir(parents=True, exist_ok=True)
@@ -223,14 +224,14 @@ def run(script: str, env: dict, script_args: list = []):
 # Temporary directory for spack
 temporary_directory_spack = tmpdir.joinpath('tmp_spack')
 temporary_directory_spack.mkdir(exist_ok=True, parents=True)
-env = env | {"JOB_TMP_SPACK": temporary_directory_spack}
+env.update({"JOB_TMP_SPACK": temporary_directory_spack})
 # make job temp folder writable for all users (i.e., spack)
 os.chmod(temporary_directory_spack, 0o777)
 
 # Directory for (temporary) spack configuration
 temporary_directory_spack_config = tmpdir.joinpath('spack_config')
 temporary_directory_spack_config.mkdir(exist_ok=True, parents=True)
-env = env | {"YASHCHIKI_SPACK_CONFIG": temporary_directory_spack_config}
+env.update({"YASHCHIKI_SPACK_CONFIG": temporary_directory_spack_config})
 # make spack config directory readable for all users (i.e., spack)
 temporary_directory_spack_config.chmod(0o755)
 
@@ -271,7 +272,7 @@ if args.recipe_filename is not None:
     recipe_filename = args.recipe_filename
 else:
     recipe_filename = tmpdir.joinpath("recipe.def")
-env = env | {"YASHCHIKI_RECIPE_PATH": recipe_filename}
+env.update({"YASHCHIKI_RECIPE_PATH": recipe_filename})
 
 # meta data directory defaults to temporary folder
 if args.meta_dir is not None:
@@ -279,7 +280,7 @@ if args.meta_dir is not None:
 else:
     meta_dir = tmpdir.joinpath("meta")
     meta_dir.mkdir(parents=True)
-env = env | {"YASHCHIKI_META_DIR": meta_dir}
+env.update({"YASHCHIKI_META_DIR": meta_dir})
 
 run("lib/yashchiki/create_caches.sh", env)
 run("lib/yashchiki/fetch.sh", env)