cli: Print a plugin suggestion on installed but expired pgp key

When PGP key for a repository is installed, but already expired, suggest enabling the expired-pgp-keys plugin to reimport the new key and resolve the issue.

dnf/base.py

@@ -2640,7 +2640,7 @@ def _prov_key_data(msg):
                     'package.\n'
                     'Check that the correct key URLs are configured for '
                     'this repository.') % repo.name
-            raise dnf.exceptions.Error(_prov_key_data(msg))
+            raise dnf.exceptions.InvalidInstalledGPGKeyError(_prov_key_data(msg))
 
         # Check if the newly installed keys helped
         result, errmsg = self._sig_check_pkg(po)

dnf/cli/cli.py

@@ -284,6 +284,7 @@ def gpgsigcheck(self, pkgs):
         :raises: Will raise :class:`Error` if there's a problem
         """
         error_messages = []
+        print_plugin_recommendation = False
         for po in pkgs:
             result, errmsg = self._sig_check_pkg(po)
 
@@ -304,6 +305,8 @@ def gpgsigcheck(self, pkgs):
                     self._get_key_for_package(po, fn)
                 except (dnf.exceptions.Error, ValueError) as e:
                     error_messages.append(str(e))
+                    if isinstance(e, dnf.exceptions.InvalidInstalledGPGKeyError):
+                        print_plugin_recommendation = True
 
             else:
                 # Fatal error
@@ -312,8 +315,9 @@ def gpgsigcheck(self, pkgs):
         if error_messages:
             for msg in error_messages:
                 logger.critical(msg)
-            logger.info("\nUse the `--enableplugin=expired-pgp-keys' "
-                        "parameter to resolve the problem.\n")
+            if print_plugin_recommendation:
+                msg = '\n' + _("Try to add '--enableplugin=expired-pgp-keys' to resolve the problem.") + '\n'
+                logger.info(msg)
             raise dnf.exceptions.Error(_("GPG check FAILED"))
 
     def latest_changelogs(self, package):

dnf/exceptions.py

@@ -86,6 +86,10 @@ def __str__(self):
         return self.errmap2str(self.errmap)
 
 
+class InvalidInstalledGPGKeyError(Error):
+    pass
+
+
 class LockError(Error):
     pass