From c80daf69204b0cc44789427ce13a9e0864a0a4d6 Mon Sep 17 00:00:00 2001
From: Nils Philippsen <nils@redhat.com>
Date: Aug 20 2018 11:42:30 +0000
Subject: explain mbs-manager exception handling


Signed-off-by: Nils Philippsen <nils@redhat.com>

---

diff --git a/pyrpkg/__init__.py b/pyrpkg/__init__.py
index a32c920..57c2169 100644
--- a/pyrpkg/__init__.py
+++ b/pyrpkg/__init__.py
@@ -3155,6 +3155,13 @@ class Commands(object):
         try:
             self._run_command(command, env=env)
         except rpkgError as e:
+            # If the exception wraps another one which has .errno == ENOENT
+            # this indicates that the file (mbs-manager executable) wasn't
+            # found. This works in both Python 2 and 3 which throw different
+            # types of exceptions in this case. We use duck-typing rather than
+            # checking for the respective specific exception types because the
+            # Python 3 FileNotFoundError exception isn't known in Python 2 and
+            # special casing this makes the code unnecessarily complicated.
             e_errno = None
             if e.args and isinstance(e.args[0], Exception):
                 e_errno = getattr(e.args[0], 'errno', None)