Restore missing part of error message (#4931)
diff --git a/Lib/distutils/core.py b/Lib/distutils/core.py
index 72e3c20..fcb2060 100644
--- a/Lib/distutils/core.py
+++ b/Lib/distutils/core.py
@@ -156,7 +156,7 @@
                 sys.stderr.write("error: %s\n" % (exc,))
                 raise
             else:
-                raise SystemExit, exc
+                raise SystemExit, "error: %s" % (exc,)
 
         except (DistutilsError,
                 CCompilerError), msg: