diff --git a/papers/commands/edit_cmd.py b/papers/commands/edit_cmd.py
index 2d379ca..6f45cc2 100644
--- a/papers/commands/edit_cmd.py
+++ b/papers/commands/edit_cmd.py
@@ -15,13 +15,12 @@ def parser(subparsers):
 
 
 def command(ui, meta, reference):
-    rp = repo.Repository.from_directory(config())
+    rp = repo.Repository(config())
     key = parse_reference(ui, rp, reference)
     paper = rp.get_paper(key)
-    to_edit = 'bib'
+    filepath = rp._bibfile(key)
     if meta:
-        to_edit = 'meta'
-    filepath = rp.path_to_paper_file(key, to_edit)
+        filepath = rp._metafile(key)
     with open(filepath) as f:
         content = f.read()
     while True:
@@ -37,9 +36,9 @@ def command(ui, meta, reference):
             new_key, bib = get_bibentry_from_string(content)
         paper.update(key=new_key, bib=bib, meta=metadata)
         try:
-            rp.update(paper, old_citekey=key)
+            rp.update_paper(paper, old_citekey=key)
             break
-        except repo.CiteKeyAlreadyExists:
+        except repo.CiteKeyCollision:
             options = ['overwrite', 'edit again', 'abort']
             choice = options[ui.input_choice(
                         options,
@@ -49,5 +48,6 @@ def command(ui, meta, reference):
             if choice == 'abort':
                 break
             elif choice == 'overwrite':
-                rp.update(paper, old_citekey=key, overwrite=True)
+                rp.update_paper(paper, old_citekey=key, overwrite=True)
+                break
             # else edit again
diff --git a/papers/files.py b/papers/files.py
index 8d0d386..fa79d03 100644
--- a/papers/files.py
+++ b/papers/files.py
@@ -165,10 +165,16 @@ def parse_bibdata(content, format_ = None):
         # we need to reuse the content
         content = content if type(content) == str else str(content.read())
 
+    # If you use StingIO from io then the content must be unicode
+    # Let call this quick fix a hack but we should think it more carefully
+    content = unicode(content)
+    # This bug was really a pain in the ass to discover because of the (old) except Expection below!
+    # I changed it to the only kind of error that can raise _parse_bibdata_formated_stream, which is a ValueError
+
     for fmt in fmts:
         try:
             return _parse_bibdata_formated_stream(StringIO(content), fmt)
-        except Exception:
+        except ValueError:
             pass
 
     raise ValueError('content format is not recognized.')
diff --git a/papers/repo.py b/papers/repo.py
index b248fb8..6bda239 100644
--- a/papers/repo.py
+++ b/papers/repo.py
@@ -117,10 +117,11 @@ class Repository(object):
     def add_paper(self, p, overwrite = False):
         if p.citekey is None:  # TODO also test if citekey is valid
             raise ValueError("Invalid citekey: {}.".format(p.citekey))
-        if not overwrite and p.citekey in self:
+        if not overwrite and p.citekey in self.citekeys:
             raise CiteKeyCollision('citekey {} already in use'.format(
                                    p.citekey))
-        self.citekeys.append(p.citekey)
+        if p.citekey not in self.citekeys:
+            self.citekeys.append(p.citekey)
         self.save_paper(p)
         self.save()
         # TODO change to logging system (17/12/2012)
@@ -143,6 +144,38 @@ class Repository(object):
         self.add_paper(paper, overwrite = overwrite)
         self._move_doc(old_citekey, paper)
 
+    def update_paper(self, paper, old_citekey=None, overwrite=False):
+        """Updates a paper, eventually changing its citekey.
+        The paper should be in repository. If the citekey changes,
+        the new citekey should be free except if the overwrite argument
+        is set to True.
+        """
+        if old_citekey is None:
+            old_citekey = paper.citekey
+        if old_citekey not in self.citekeys:
+            raise(ValueError, 'Paper not in repository. Add first')
+        else:
+            if paper.citekey == old_citekey:
+                self.save_paper(paper)
+            else:
+                if paper.citekey in self.citekeys:
+                    if not overwrite:
+                        raise(CiteKeyCollision,
+                            "There is already a paper with citekey: %s."
+                                % paper.citekey)
+                    else:
+                        self.save_paper(paper)
+                else:
+                    self.add_paper(paper)
+                # Eventually move document file
+                paper = PaperInRepo.from_paper(paper, self)
+                try:
+                    path = self.find_document(old_citekey)
+                    self.import_document(paper.citekey, path)
+                except NoDocumentFile:
+                    pass
+                self.remove_paper(old_citekey, remove_doc=True)
+
     def _move_doc(self, old_citekey, paper):
         """Fragile. Make more robust"""
         try:
@@ -160,7 +193,7 @@ class Repository(object):
     def _metafile(self, citekey):
         return os.path.join(self.meta_dir, citekey + '.meta')
 
-    def remove_paper(self, citekey, remove_doc = True):
+    def remove_paper(self, citekey, remove_doc=True):
         paper = self.get_paper(citekey)
         self.citekeys.remove(citekey)
         os.remove(self._metafile(citekey))