Add safeguard against improper installs when using a clean repository checkout. Fixes #659.

CHANGES.rst

@@ -2,6 +2,12 @@
 CHANGES
 =======
 
+v24.1.0
+-------
+
+* #659: ``setup.py`` now will fail fast and with a helpful
+  error message when the necessary metadata is missing.
+
 v24.0.3
 -------
 

setup.py

@@ -11,6 +11,11 @@ import textwrap
 # Allow to run setup.py from another directory.
 os.chdir(os.path.dirname(os.path.abspath(__file__)))
 
+# Prevent improper installs without necessary metadata. See #659
+if not os.path.exists('setuptools.egg-info'):
+    msg = "Cannot build setuptools without metadata. Run bootstrap.py"
+    raise RuntimeError(msg)
+
 src_root = None
 
 from distutils.util import convert_path