[buildcore] Fix pybb mkdir

deps/buildcore/scripts/pybb.py

@@ -31,9 +31,15 @@ def cat(paths: str) -> int:
 
 
 def mkdir(path: str) -> int:
-    if not os.path.exists(path) and os.path.isdir(path):
-        os.mkdir(path)
-    return 0
+    if not os.path.exists(path):
+        try:
+            os.mkdir(path)
+        except:
+            return 1
+        return 0
+    if os.path.isdir(path):
+        return 0
+    return 1
 
 
 # this exists because Windows is utterly incapable of providing a proper rm -rf