Backport PR #5503: check explicitly for 'dev' before adding the note to docs

allows 'maint' suffix (or similar) for the maintenance branches, so they don't get the note on every page.

docs/source/conf.py

@@ -68,12 +68,12 b" templates_path = ['_templates']"
 # The suffix of source filenames.
 source_suffix = '.rst'
 
-if iprelease['_version_extra']:
+if iprelease['_version_extra'] == 'dev':
     rst_prolog = """
     .. note::
 
         This documentation is for a development version of IPython. There may be
-        significant differences from the latest stable release (1.2.1).
+        significant differences from the latest stable release.
 
     """
 
@@ -82,7 +82,7 b" master_doc = 'index'"
 
 # General substitutions.
 project = 'IPython'
-copyright = '2008, The IPython Development Team'
+copyright = 'The IPython Development Team'
 
 # ghissue config
 github_project_url = "https://github.com/ipython/ipython"