fix: spackdir not needed for stage "build-base-image"

Change-Id: I8fb1fe396c83c50eabd57cf09012c63adc6923ba

bin/yashchiki

@@ -134,9 +134,6 @@ args = parser.parse_args()
 root_dir = pathlib.Path(__file__).parent.parent
 
 # check provided paths
-if not args.spack_dir.is_dir():
-    raise NotADirectoryError("spack_dir is required to be a path to an "
-                             "existing directory.")
 if (args.meta_dir is not None) and (not args.meta_dir.is_dir()):
     raise NotADirectoryError("meta-dir is required to be a path to an "
                              "existing directory.")
@@ -191,14 +188,19 @@ env.update({
     "YASHCHIKI_JOBS": str(args.jobs),
 })
 
+needs_spackdir = False
+
 if "fetch" in args.stages:
     env.update({"YASHCHIKI_ENABLE_STAGE_FETCH": "1"})
+    needs_spackdir = True
 
 if "build-base" in args.stages:
     env.update({"YASHCHIKI_ENABLE_STAGE_BUILD_BASE": "1"})
+    needs_spackdir = True
 
 if "build-spack" in args.stages:
     env.update({"YASHCHIKI_ENABLE_STAGE_BUILD_SPACK": "1"})
+    needs_spackdir = True
 
 if "image" in args.stages:
     env.update({"YASHCHIKI_ENABLE_STAGE_IMAGE": "1"})
@@ -207,6 +209,11 @@ if args.stages != all_stages:
     if not pathlib.Path(args.sandboxes_dir, args.style).exists():
         raise RuntimeError("Using yashchiki with incomplete set of stages is only possible for using an existing sandbox.")
 
+if needs_spackdir:
+    if not args.spack_dir.is_dir():
+        raise NotADirectoryError("spack_dir is required to be a path to an "
+                                 "existing directory.")
+
 if args.build_cache_on_failure_name:
     env.update({"YASHCHIKI_BUILD_CACHE_ON_FAILURE_NAME": args.build_cache_on_failure_name})