ppc64le: Add to the list of architectures

Bug: 1120487
abort the entire worker process if session.close() fails

If we fail to close the session (for example because of an out-of-memory
condition) we want the entire worker process to abort, because any
subsequent requests will fail due to the transaction left open. Under
mod_wsgi daemon mode the worker will just be replaced with a fresh one.

Also removed superfluous session.rollback() call from the close_session
handler. The commit_or_rollback_session handler would already have tried
to call session.rollback(), so if that failed for some reason then
trying again will only make things worse. session.close() will
ultimately send a ROLLBACK to the database as part of releasing the
connection anyway, which is really what we care about.

Bug: 1120439
Change-Id: Ibd6cd6deb924a9e91f586ff841c4dd24859131ec
prevent duplicate users due to LDAP whitespace normalization

Bug: 1121748
Change-Id: I3b6563295699414ac867c1c14f0b3b9bd4addf83
Support for PPC64 grub2 netboot

Bug: 1113816
Change-Id: Icb08cbfe44ad85e8c4a34a645a77e3a1bcf2361a
Fix for regression that recipe-task can not be cancelled by CLI

bug: 1124756
Change-Id: Ic1f46e75137e2c81c76f26553f2e42174ef39024
fix mistake in db downgrade notes for 0.17

We need to add back the lab_controller.user_id index in the same ALTER
TABLE statement, because the column is involved in an InnoDB foreign key
and InnoDB requires an index on it.

    ERROR 1553 (HY000): Cannot drop index 'uc_user_id': needed in a foreign key constraint

Change-Id: Idff5fce194fca70c58a6dbf22cf048635895e8e2
set netboot_method= for GRUB2

Change-Id: Ia748f219af045aa6709ceef16cdb32a21584c917
release notes for 0.17.3

Change-Id: I2495e7b5ef841b7b95b792f79eafeea281d8d4ee
Automatic commit of release 0.17.3