Don't check for sudo environment if vendored sources are already configured

Author: djc

src/bootstrap/bootstrap.py

@@ -438,7 +438,7 @@ def main():
     rb.use_vendored_sources = '\nvendor = true' in rb.config_toml or \
                               'CFG_ENABLE_VENDOR' in rb.config_mk
 
-    if 'SUDO_USER' in os.environ:
+    if 'SUDO_USER' in os.environ and not rb.use_vendored_sources:
         if os.environ['USER'] != os.environ['SUDO_USER']:
             rb.use_vendored_sources = True
             print('info: looks like you are running this command under `sudo`')