Jython 2.7.4 final

Jython 2.7.4rc1

Jython 2.7.4b2

Jython 2.7.4b1

Jython 2.7.3

Jython 2.7.3rc1

Jython 2.7.3b1

Prepare for 2.7.2 final release.

Prepare for 2.7.2rc1 release.

Update version numbers. Add jffi-dll-droppings to .hgignore so as to avoid
complaints from the build after test.

Establish java environment in test_jython_initializer (fixes #2810)

This change addresses a test failure observed in test_jython_initializer
where the build Java is ahead of the default installed Java.
We "inherit" java.home in the otherwise-stripped environment.