Improve package version constraint suggestions.

app/models/package_version.py

 # Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 
 import copy
 import json
 import tarfile
 
 from google.appengine.api import memcache
 from google.appengine.ext import db
@@ skipping 226 matching lines @@
 
         return map(self._import_for_library, self.libraries)
 
     def _import_for_library(self, library):
         """Return the import information for a library in this package."""
         return {'package': self.package.name, 'library': library}
 
     @property
     def example_version_constraint(self):
         """Return the example version constraint for this package."""
-        if self.version.in_initial_development:
-            return json.dumps(">=%s <%d.%d.0" %
-                (self.version, self.version.major, self.version.minor + 1))
-        return json.dumps(
-            ">=%s <%d.0.0" % (self.version, self.version.major + 1))
+        # TODO(nweiz): Once the 1.11 SDK is out and pub supports ">=1.2.3-pre
+        # <1.2.3", suggest that as the version constraint for prerelease
+        # versions.
+        return json.dumps("^%s" % self.version)
 
     @property
     def storage_path(self):
         """The Cloud Storage path for this package."""
         # Use the canonical version for the cloud storage path for
         # backwards-compatibility with package versions that were uploaded
         # prior to storing non-canonicalized versions.
         return 'packages/%s-%s.tar.gz' % \
             (self.package.name, self.version.canonical)
 
@@ skipping 49 matching lines @@
 
         if full:
             value.update({
                 'created': self.created.isoformat(),
                 'downloads': self.downloads,
                 'libraries': self.libraries,
                 'uploader': self.uploaderEmail
             })
 
         return value