gnome-doc-utils: Port to Python 3

See #1935

gnome-doc-utils/more-python3-fixes.patch

@@ -0,0 +1,62 @@
+diff -Nur gnome-doc-utils-0.20.10-orig/xml2po/xml2po/__init__.py gnome-doc-utils-0.20.10/xml2po/xml2po/__init__.py
+--- gnome-doc-utils-0.20.10-orig/xml2po/xml2po/__init__.py	2020-05-01 19:15:02.937514100 +0200
++++ gnome-doc-utils-0.20.10/xml2po/xml2po/__init__.py	2020-05-01 19:31:34.676207600 +0200
+@@ -259,7 +259,7 @@
+                     if not self.expand_entities:
+                         result += '&' + child.name + ';'
+                     else:
+-                        result += child.content.decode('utf-8')
++                        result += child.content
+                 else:
+                     result += self.myAttributeSerialize(child)
+                 child = child.next
+@@ -338,7 +338,7 @@
+                 pass
+ 
+             if not newnode:
+-                print("""Error while parsing translation as XML:\n"%s"\n""" % (text.encode('utf-8')), file=sys.stderr)
++                print("""Error while parsing translation as XML:\n"%s"\n""" % (text), file=sys.stderr)
+                 return
+ 
+             newelem = newnode.getRootElement()
+@@ -423,7 +423,7 @@
+         outtxt = self.normalizeString(attr.content)
+         if self.app.operation == 'merge':
+             translation = self.app.getTranslation(outtxt)
+-            self.replaceAttributeContentsWithText(attr, translation.encode('utf-8'))
++            self.replaceAttributeContentsWithText(attr, translation)
+         else:
+             self.app.msg.outputMessage(outtxt, node.lineNo(),  "", spacepreserve=False,
+                               tag = node.name + ":" + attr.name)
+@@ -464,7 +464,7 @@
+             norm_outtxt = self.normalizeString(outtxt, self.app.isSpacePreserveNode(node))
+             translation = self.app.getTranslation(norm_outtxt)
+         else:
+-            translation = outtxt.decode('utf-8')
++            translation = outtxt
+ 
+         starttag = self.startTagForNode(node)
+         endtag = self.endTagForNode(node)
+@@ -504,7 +504,7 @@
+             # !!! This is not very nice thing to do, but I don't know if
+             #     raising an exception is any better
+             return False
+-        return tmpstr.find('EXTERNAL_GENERAL_PARSED_ENTITY') != -1
++        return tmpstr.find(b'EXTERNAL_GENERAL_PARSED_ENTITY') != -1
+ 
+     def doSerialize(self, node):
+         """Serializes a node and its children, emitting PO messages along the way.
+@@ -552,11 +552,11 @@
+         self.current_mode = self.load_mode(mode)()
+         # Prepare output
+         if operation == 'update':
+-            self.out = tempfile.TemporaryFile()
++            self.out = tempfile.TemporaryFile("w+", encoding="utf-8")
+         elif output == '-':
+             self.out = sys.stdout
+         else:
+-            self.out = file(output, 'w')
++            self.out = open(output, 'w', encoding="utf-8")
+ 
+     def load_mode(self, modename):
+         try: