convert: use raw strings for XML strings

Due to the source transformer, we were passing bytes into the
XML APIs. This results in not finding elements and doing compares
against mismatched types.

Use raw string literals so we use str everywhere.

Differential Revision: https://phab.mercurial-scm.org/D5664

hgext/convert/subversion.py

@@ -1183,11 +1183,11 b' class svn_sink(converter_sink, commandli'
         m = set()
         output = self.run0('ls', recursive=True, xml=True)
         doc = xml.dom.minidom.parseString(output)
-        for e in doc.getElementsByTagName('entry'):
+        for e in doc.getElementsByTagName(r'entry'):
             for n in e.childNodes:
-                if n.nodeType != n.ELEMENT_NODE or n.tagName != 'name':
+                if n.nodeType != n.ELEMENT_NODE or n.tagName != r'name':
                     continue
-                name = ''.join(c.data for c in n.childNodes
+                name = r''.join(c.data for c in n.childNodes
                                if c.nodeType == c.TEXT_NODE)
                 # Entries are compared with names coming from
                 # mercurial, so bytes with undefined encoding. Our