behave gracefully if no GExiv2 under Python3

svn: r21467

gramps/grampsapp.py

@@ -240,11 +240,17 @@ def show_settings():
         osmgpsmap_str = 'not found'
 
     try:
+        from gi import Repository
+        repository = Repository.get_default()
+        if repository.enumerate_versions("GExiv2"):
             from gi.repository import GExiv2
             try:
                 gexiv2_str = GExiv2._version
             except: # any failure to 'get' the version
                 gexiv2_str = 'unknown version'
+        else:
+            gexiv2_str = 'not found'
+
     except ImportError:
         gexiv2_str = 'not found'
 

gramps/plugins/gramplet/gramplet.gpr.py

@@ -371,12 +371,14 @@ register(GRAMPLET,
          )
 
 try:
+    from gi import Repository
+    repository = Repository.get_default()
+    if repository.enumerate_versions("GExiv2"):
         from gi.repository import GExiv2
         available = True
-except:
-    import logging
-    logging.warning(_("WARNING: GExiv2 module not loaded.  "
-                      "Image metadata functionality will not be available."))
+    else:
+        available = False
+except ImportError:
     available = False
 
 if available: