hot str_replace behaves differently to Fn::Replace

[Steve Baker]

str_replace uses python templates, whereas Fn::Replace uses python string.replace.

During the original review for Fn::Replace, python templates were decided against because $ would often need double-escaping in shell scripts.
https://review.openstack.org/#/c/31736/

As a fix, str_replace should switch to using string.replace

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/47772

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/47772
Committed: http://github.com/openstack/heat/commit/f424d6f6c3fec5a534c7850551ad62b4f055b606
Submitter: Jenkins
Branch: master

commit f424d6f6c3fec5a534c7850551ad62b4f055b606
Author: Steve Baker <email address hidden>
Date: Mon Sep 23 13:41:32 2013 +1200

    HOT str_replace to use string.replace, not string.Template

    str_replace uses python templates, whereas Fn::Replace uses python
    string.replace.

    During the original review for Fn::Replace, python templates were
    decided against because $ would often need double-escaping in shell scripts.
    https://review.openstack.org/#/c/31736/

    Having different behaviours between Fn::Replace and str_replace will
    add complication for users migrating existing templates to HOT.

    Another advantage of using straight string replacement is seen when
    the template generates a executable script. In this case it is generally
    possible to write a template that can also be executed directly in a
    dev/test environment. This would often not be possible if the template
    format required placeholders to be prefixed with a $.

    Whatever behaviour exists when Havana is release will have to be
    supported indefinitely so now is the time to decide if this is going
    to be fixed.

    Closes-Bug: #1228640
    Change-Id: I72879b374a3c61dfe0e4004251ab709d914f2e25