BUG: Empty old project report

The parent directory is used in a test, but it did not have the same name when the project was checkout in the old worktree.

* Insert the parent directory name in the worktree.

Makefile

@@ -409,7 +409,7 @@ ifndef $($/_HOME_DIR)
     endef
     $(eval $(META))
 endif
-$/_OLD := $($/_HOME)build/$($/_BASELINE)/$/
+$/_OLD := $($/_HOME)build/$($/_BASELINE)/$($/_NAME)/$/
 
 ## Colorize edited files by their git status
 NORMAL ?= `tput sgr0`