Display dev version constraints based on current Dart team policies.

app/models/package_version.py

Index: app/models/package_version.py
diff --git a/app/models/package_version.py b/app/models/package_version.py
index bed00794fc07ce0b48fb5f26194bcbf0b96e5042..f216f0e9b08637e2892d66350a78fafc6faf2cc1 100644
--- a/app/models/package_version.py
+++ b/app/models/package_version.py
@@ -196,7 +196,9 @@ class PackageVersion(db.Model):
     @property
     def example_version_constraint(self):
         """Return the example version constraint for this package."""
-        if self.version.in_initial_development: return str(self.version)
+        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))