Use shorter encoding of UUID when using UUID as id

src/calibre/ebooks/oeb/base.py

@@ -6,7 +6,7 @@ __license__   = 'GPL v3'
 __copyright__ = '2008, Marshall T. Vandegrift <llasram@gmail.com>'
 __docformat__ = 'restructuredtext en'
 
-import os, re, uuid, logging
+import os, re, logging
 from collections import defaultdict
 from itertools import count
 from urlparse import urldefrag, urlparse, urlunparse, urljoin
@@ -21,6 +21,7 @@ from calibre import (isbytestring, as_unicode, get_types_map)
 from calibre.ebooks.oeb.parse_utils import (barename, XHTML_NS, RECOVER_PARSER,
         namespace, XHTML, parse_html, NotHTML)
 from calibre.utils.cleantext import clean_xml_chars
+from calibre.utils.short_uuid import uuid4
 
 XML_NS       = 'http://www.w3.org/XML/1998/namespace'
 OEB_DOC_NS   = 'http://openebook.org/namespaces/oeb-document/1.0/'
@@ -100,7 +101,7 @@ def close_self_closing_tags(raw):
     return _self_closing_pat.sub(r'<\g<tag>\g<arg>></\g<tag>>', raw)
 
 def uuid_id():
-    return 'u'+unicode(uuid.uuid4())
+    return u'u'+uuid4()
 
 def itercsslinks(raw):
     for match in _css_url_re.finditer(raw):

src/calibre/ebooks/oeb/polish/check/opf.py

@@ -191,9 +191,9 @@ class NoUID(BaseError):
         BaseError.__init__(self, _('The OPF has no unique identifier'), name)
 
     def __call__(self, container):
-        import uuid
+        from calibre.ebooks.oeb.base import uuid_id
         opf = container.opf
-        uid = 'u' + str(uuid.uuid4())
+        uid = uuid_id()
         opf.set('unique-identifier', uid)
         m = container.opf_xpath('/opf:package/opf:metadata')
         if not m:

src/calibre/ebooks/oeb/polish/check/parsing.py

@@ -344,9 +344,9 @@ class InvalidId(BaseError):
         self.invalid_id = eid
 
     def __call__(self, container):
-        import uuid
+        from calibre.ebooks.oeb.base import uuid_id
         from calibre.ebooks.oeb.polish.replace import replace_ids
-        newid = 'g' + uuid.uuid4().hex
+        newid = uuid_id()
         changed = False
         elems = (e for e in container.parsed(self.name).xpath('//*[@id]') if e.get('id') == self.invalid_id)
         for e in elems: