Fix pylint warnings about string formatting

and one about unused exception value.

src/bin/image-minimizer

@@ -179,7 +179,7 @@ def main():
         minimizer.filter()
     except SystemExit as e:
         sys.exit(e.code)
-    except KeyboardInterrupt as e:
+    except KeyboardInterrupt:
         print("Aborted at user request")
 
 if __name__ == "__main__":

src/sbin/livemedia-creator

@@ -115,7 +115,7 @@ def main():
         opts.image_type = "qcow2"
 
     if opts.image_type and not os.path.exists("/usr/bin/qemu-img"):
-        errors.append("image-type requires the qemu-img utility to be installed." % opts.image_type)
+        errors.append("image-type option requires the qemu-img utility to be installed.")
 
     if opts.image_type and opts.make_iso:
         errors.append("image-type cannot be used to make a bootable iso.")

src/sbin/lorax

@@ -170,14 +170,14 @@ def main():
     for kv in opts.add_template_vars:
         k, t, v = kv.partition('=')
         if t == '':
-            raise ValueError("Missing '=' for key=value in " % kv)
+            raise ValueError("Missing '=' for key=value in %s" % kv)
         parsed_add_template_vars[k] = v
 
     parsed_add_arch_template_vars = {}
     for kv in opts.add_arch_template_vars:
         k, t, v = kv.partition('=')
         if t == '':
-            raise ValueError("Missing '=' for key=value in " % kv)
+            raise ValueError("Missing '=' for key=value in %s" % kv)
         parsed_add_arch_template_vars[k] = v
 
     if 'SOURCE_DATE_EPOCH' in os.environ: