feature: Allow developers to use Spack for partial builds (#12006)

Added new diy option.

lib/spack/spack/cmd/diy.py

@@ -38,6 +38,9 @@ def setup_parser(subparser):
     subparser.add_argument(
         '-q', '--quiet', action='store_true', dest='quiet',
         help="do not display verbose build output while installing")
+    subparser.add_argument(
+        '-u', '--until', type=str, dest='until', default=None,
+        help="phase to stop after when installing (default None)")
     subparser.add_argument(
         'spec', nargs=argparse.REMAINDER,
         help="specs to use for install. must contain package AND version")
@@ -90,4 +93,5 @@ def diy(self, args):
         install_deps=not args.ignore_deps,
         verbose=not args.quiet,
         keep_stage=True,   # don't remove source dir for DIY.
-        dirty=args.dirty)
+        dirty=args.dirty,
+        stop_at=args.until)