Fixes (iptest), simplified v1, v2, .. , vX import code

IPython/nbformat/current.py

@@ -62,7 +62,7 b' def parse_py(s, **kwargs):'
 
 def reads_json(s, **kwargs):
     """Read a JSON notebook from a string and return the NotebookNode object."""
-    return convert(reader.reads(nb), current_nbformat)
+    return convert(reader.reads(s), current_nbformat)
 
 
 def writes_json(nb, **kwargs):

IPython/nbformat/reader.py

@@ -18,9 +18,15 b' Authors:'
 
 import json
 
-versions = {}
-for i in range(3):
-    versions[i+1] = __import__('v{0}'.format(i+1))
+import v1
+import v2
+import v3
+
+versions = {
+    1: v1,
+    2: v2,
+    3: v3,
+    }
 
 #-----------------------------------------------------------------------------
 # Code
@@ -76,7 +82,7 b" def reads(s, format='ipynb', **kwargs):"
     nb_dict = parse_json(s, **kwargs)
     (major, minor) = get_version(nb_dict)
     if major in versions:
-        return versions[major].to_notebook_json(nb, minor=minor)
+        return versions[major].to_notebook_json(nb_dict, minor=minor)
     else:
         raise NBFormatError('Unsupported nbformat version %s' % major)
 

IPython/nbformat/v1/__init__.py

@@ -20,4 +20,4 b' from .nbjson import reads as reads_json, writes as writes_json'
 from .nbjson import reads as read_json, writes as write_json
 from .nbjson import to_notebook as to_notebook_json
 
-from .convert import downgrade, upgrade
+from .convert import upgrade