[Merge] lp:~bhargav-golla/postorius/bug-1294463 into lp:postorius

[Terri]

Review: Approve

Looks good!  

Florian and I had a quick chat to see if we could think of a way to do this without a REST call, but we're pretty sure we don't have the info requested already at this point, so this is probably as efficient as it gets.  I'll be merging it shortly.
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https://code.launchpad.net/~bhargav-golla/postorius/bug-1294463/+merge/212167
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