fix bugs found with stricter flake8 rules

- When you don't use wildcards, flake8 will find places where you used an
  undefined name.

- This commit has all the bugfixes resulting from this static check.

lib/spack/llnl/util/tty/colify.py

@@ -188,7 +188,7 @@ def colify(elts, **options):
     elif method == "uniform":
         config = config_uniform_cols(elts, console_cols, padding, cols)
     else:
-        raise ValueError("method must be one of: " + allowed_methods)
+        raise ValueError("method must be either 'variable' or 'uniform'")
 
     cols = config.cols
     rows = (len(elts) + cols - 1) // cols