Appengine Search API - Globally Consistent
This depends on whether or not you have any globally consistent indexes. If you do, then you should migrate all of your data from those indexes to new, per-document-consistent (which is the default) indexes. To do this:

Loop through the documents you have stored in the global index and reindexing them in the new index.
Change references from the global index to the new per-document index.
Ensure everything works, then delete the documents from your global index (not necessary to complete the migration, but still a good idea).

You then should remove any mention of consistency from your code; the default is per-document consistent, and eventually we will remove the ability to specify a consistency at all.  
If you don't have any data in a globally consistent index, you're probably getting the warning because you're specifying a consistency. If you stop specifying the consistency it should go away.  
Note that there is a known issue with the Python API that causes a lot of erroneous deprecation warnings about consistency, so you could be seeing that as well. That issue will be fixed in the next release.
I've been using the appengine python experimental searchAPI. It works great. With release 1.7.3 I updated all of the deprecated methods. However, I am now getting this warning:
DeprecationWarning: consistency is deprecated. GLOBALLY_CONSIST
However, I'm not sure how to address it in my code. Can anyone point me in the right direction?