[FIX] base_gengo: do not crash if Gengo is not present

Before this commit, calling gengo_authentication (executed from the
cron _send_translation_terms) returns an error when the python library
gengo is not found on the system.
If tried to request a synchronisation, got an error "NameError: name
'Gengo' is not defined"
Gengo variable was undefined as no imported.

closes odoo/odoo#40686

X-original-commit: 675b355954522caf7d72ab20cc431d19c5a05a8f
Signed-off-by: Martin Trigaux (mat) <mat@odoo.com>

addons/base_gengo/i18n/base_gengo.pot

@@ -4,10 +4,10 @@
 #
 msgid ""
 msgstr ""
-"Project-Id-Version: Odoo Server saas~12.5\n"
+"Project-Id-Version: Odoo Server 13.0\n"
 "Report-Msgid-Bugs-To: \n"
-"POT-Creation-Date: 2019-08-26 08:16+0000\n"
-"PO-Revision-Date: 2019-08-26 08:16+0000\n"
+"POT-Creation-Date: 2019-11-22 08:19+0000\n"
+"PO-Revision-Date: 2019-11-22 08:19+0000\n"
 "Last-Translator: \n"
 "Language-Team: \n"
 "MIME-Version: 1.0\n"
@@ -179,6 +179,13 @@ msgid ""
 "``%s``"
 msgstr ""
 
+#. module: base_gengo
+#: code:addons/base_gengo/wizard/base_gengo_translations.py:0
+#, python-format
+msgid ""
+"Gengo library not installed. Contact your system administrator to use it."
+msgstr ""
+
 #. module: base_gengo
 #: model:ir.actions.act_window,name:base_gengo.action_wizard_base_gengo_translations
 #: model:ir.ui.menu,name:base_gengo.menu_action_wizard_base_gengo_translations

addons/base_gengo/wizard/base_gengo_translations.py

@@ -15,6 +15,7 @@ _logger = logging.getLogger(__name__)
 try:
     from gengo import Gengo
 except ImportError:
+    Gengo = None
     _logger.warning('Gengo library not found, Gengo features disabled. If you plan to use it, please install the gengo library from http://pypi.python.org/pypi/gengo')
 
 GENGO_DEFAULT_LIMIT = 20
@@ -78,6 +79,8 @@ class BaseGengoTranslations(models.TransientModel):
         user = self.env.user
         if not user.company_id.gengo_public_key or not user.company_id.gengo_private_key:
             return (False, _("Gengo `Public Key` or `Private Key` are missing. Enter your Gengo authentication parameters under `Settings > Companies > Gengo Parameters`."))
+        if not Gengo:
+            return (False, _("Gengo library not installed. Contact your system administrator to use it."))
         try:
             gengo = Gengo(
                 public_key=user.company_id.gengo_public_key.encode('ascii'),