7258: Metadata viewer: Exiv2 can't handle Windows's UTF16 pathnames

So open the file and pass the handle.

gramps/plugins/lib/libmetadata.py

@@ -178,13 +178,13 @@ class MetadataView(Gtk.TreeView):
         self.sections = {}
         self.model.clear()
 
-        if os.path.exists(full_path):
+        if not os.path.exists(full_path):
+            return False
+
+        retval = False
+        with open(full_path, 'rb') as fd:
             try:
-                metadata = GExiv2.Metadata(full_path)
+                metadata = GExiv2.Metadata(self.fd)
-            except:
-                return False
-        else:
-            return False
 
                 get_human = metadata.get_tag_interpreted_string
 
@@ -212,7 +212,11 @@ class MetadataView(Gtk.TreeView):
                 self.model.add((label, human_value), node=node)
 
                 self.model.tree.expand_all()
-        return self.model.count > 0
+                retval = self.model.count > 0
+            except:
+                pass
+
+        return retval
 
     def __add_section(self, section):
         """
@@ -229,15 +233,17 @@ class MetadataView(Gtk.TreeView):
         """
         Return True if the gramplet has data, else return False.
         """
-        if os.path.exists(full_path):
+        if not os.path.exists(full_path):
+            return False
+        with open(full_path, 'rb') as fd:
+            retval = False
             try:
-                metadata = GExiv2.Metadata(full_path)
+                metadata = GExiv2.Metadata(fd)
-            except:
-                return False
-        else:
-            return False
-
                 for tag in TAGS:
                     if tag in metadata.get_exif_tags():
-                return True
+                        retval = True
-        return False
+                        break
+            except:
+                pass
+
+        return retval