taking care of some IOErrors

[Chris Lumens <clumens redhat com>]

I know it's impossible to predict where all the IOErrors coming from bad
media could happen.  However I get the feeling that most are coming from
repo.getPackage in yuminstall.py.  With that said, I propose the
following patch:

diff --git a/yuminstall.py b/yuminstall.py
index 9303607..61980e4 100644
--- a/yuminstall.py
+++ b/yuminstall.py
@@ -171,6 +171,15 @@ class AnacondaCallback:
 
                     f = open(fn, 'r')
                     self.openfile = f
+                except IOError, e:
+                    if e.errno == 5:
+                        self.messageWindow(_("Error"), _("An error occurred "
+                            "reading the package %s.  This is probably due to "
+                            "bad media.  Please verify your disc with media "
+                            "check.  The installer will now exit.") % pkgStr,
+                            type="custom", custom_icon="error",
+                            custom_buttons=[_("_Exit installer")])
+                    sys.exit(1)
                 except yum.Errors.NoMoreMirrorsRepoError:
                     self.ayum._handleFailure(po)
                 except yum.Errors.RepoError, e:

We can tweak the error message a little bit.  And we can add this same
block in one or two other places later on if need be.  I think this will
probably take care of at least 67% of the IOError tracebacks we're
seeing.  Live CD installs can probably also be fixed up with just one or
two of these blocks.  Objections?

- Chris