stack lock release when acquire

[huangtianhua]

1. create a stack with a nova server
2. the stack in CREATE_IN_PROGRESS, the nova server in BUILD
3. try to update the stack
4. an error raised: ERROR: Stack ic already has an action (CREATE) in progress.
5. describe: stack in CREATE_IN_PROGRESS and the nova server in BUILD still
6. try to update again
7. then the stack change to UPDATE_FAILED

excepted: The step7 should raise the error as step4
I found in step4, the stack and engine lock is released due to the exception, and I think it's incorrect.
########################
@contextlib.contextmanager
def thread_lock(self, stack_id):
      try:
            self.acquire()
            yield
        except: # noqa
            with excutils.save_and_reraise_exception():
                self.release(stack_id)
#################

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/153186

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/153186
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=00c599319577730fcd085d9645fbe14a7f61c4ee
Submitter: Jenkins
Branch: master

commit 00c599319577730fcd085d9645fbe14a7f61c4ee
Author: huangtianhua <email address hidden>
Date: Thu Feb 5 15:29:54 2015 +0800

    Release stack lock when successfully acquire

    Should not to release the stack lock if acquire failed,
    such as stack action in progress.

    Change-Id: I2a519c47306065b0a3412a8c6faa64006dea691f
    Closes-Bug: #1418360

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: stable/juno
Review: https://review.openstack.org/161144

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/161144
Committed: https://git.openstack.org/cgit/openstack/heat/commit/?id=691a06adb2f241fdbc8ca887ccc553c1f184ece7
Submitter: Jenkins
Branch: stable/juno

commit 691a06adb2f241fdbc8ca887ccc553c1f184ece7
Author: huangtianhua <email address hidden>
Date: Thu Feb 5 15:29:54 2015 +0800

    Release stack lock when successfully acquire

    Should not to release the stack lock if acquire failed,
    such as stack action in progress.

    Change-Id: I2a519c47306065b0a3412a8c6faa64006dea691f
    Closes-Bug: #1418360
    (cherry picked from commit 00c599319577730fcd085d9645fbe14a7f61c4ee)