hghave: add "absimport" feature to check "absolute_import" in __future__
This patch adds "absimport" feature to check whether "absolute_import"
exists in __future__, which means supporting module loading by
absolute name.
This check is needed for portability of test code using
"absolute_import", because Python earlier than 2.5 doesn't support it.
[ original upstream message ]
run-tests: place the .t shell script next to $TESTTMP and with a useful name
--keep can thus keep it around - very convenient for debugging.
[ original upstream message ]