GAE SDK for Python 2.5
Dave W. Smith gave me the answer but I didn't know how to implement it until I made a discovery that maybe most people already know, But in case it might be helpful to somebody, I will tell it here: 
I do all my GAE/Python/Flex development work in Eclispe, except that I used the launcher for local testing and deploying. (I am command-line adverse.) I discovered that using the PyDev Eclipse plugin it is easy to set up a "run configuration" (under the PyDev "Run" menu) whereby you can set up command line parameters, etc. and run any python program from within Eclipse. I now use that facility for running dev_appserver.py (and when needed for my Python 2.5 app, old_app_devserver.py). I no longer have a need to use the launcher. I also set up a PyDev run configuation to deploy my app and performing various appcfg.py functions (vacuum indexes, etc.).
I have an existing app that uses the deprecated Python 2.5 and the deprecated master/slave datastore. According to the docs, I must migrate the datastore to HRD before I can upgrade to Python 2.7. Before I can migrate my M/S datastore to HRD, I need to do some work on the app and test it using the dev server. 
However, I upgraded to the most recent version of the SDK (1.8.6), and it does not support Python 2.5. Somebody else encountered this problem and learned that the latest SDK that supports Python 2.5 by default is Python SDK 1.7.5. From where can that be downloaded? Or, is there a way I can make the SDK 1.8.6 work with Python 2.5?