fallback handling

[Kyle Nitzsche]

New Description:
Child scopes that provide results that lack an "art" attribute trigger fallback code. This sometimes fails and throws the uncaught exception listed in the Old Description. El Pais scope and Yahoo scope are known to provide such partial results.

Old Description:
When el pais is enabled and you refresh the default Headlines dept, one gets this exception in the scope-registry.log:

[2016-07-07 14:02:05.651] ERROR: com.canonical.scopes.news_unity-scope-news: ReplyObject::push(): ReplyObject::push(VariantMap): unity::LogicException: Variant does not contain a string value:
    boost::bad_get: failed value get using boost::get
query complete, status: error

: ReplyObject::push(VariantMap): unity::LogicException: Variant does not contain a string value:
    boost::bad_get: failed value get using boost::get

Removing el pais causes no such logged exceptions.

[Kyle Nitzsche (knitzsche)]

The problem here is in the scope-aggregator code that attempts to use fallback result fields to find art. If the result lacks the expected field, the declared fallback fields are checked in sequence. The code can try to read a result attribute that does not exist, and so an exception is thrown.

[Kyle Nitzsche (knitzsche)]

4.9 scope-aggregator is released, fixing the fallback handling bug.

[Kyle Nitzsche (knitzsche)]

News scope 4.9.0 is released and attached here (but not added to clicks) including this rebase/fix.

Testing doc: https://docs.google.com/document/d/1a6ad4IKefC8jhzAoYFIgDqd3VcofSg-fq_kGSnx3a9I/edit#

[Kyle Nitzsche (knitzsche)]

Today scope 4.9.0 is released and attached here (but not added to clicks), including this fix.

Testing doc: https://docs.google.com/document/d/1BdmVF3F2ZYJr-ErY4M7MeZrIL8olQHZCV7rze7eWiL0/edit#

[Kyle Nitzsche (knitzsche)]

Nearby scope 4.9.0 is ready and attached here (but not added to clicks), including this fix.

Testing doc: https://docs.google.com/document/d/1pTSM8DufocwVVfKjtx3YNrHvIcW3jQ7KBoM475hBjSY/edit#

[Kyle Nitzsche (knitzsche)]

Photos scope 4.9.0 is ready and attached here (but not added to clicks), including this fix and two others:
* Dropbox scope ID is fixed (it changed to dropboxcp.canonicalpartners_dropbox)
* Douban declaration is simplified (no user detectable change though)

Testing doc: https://docs.google.com/document/d/1UhxVoFJ5ISseyrN7AH7uQ3h7E88kOM9dX1ucVj-JWCs/edit#

[Kyle Nitzsche (knitzsche)]

Hi Penk,

This bug now contains the 4.9.0 clicks for the four euro agg scopes to fix this bug for QA and release in ota 13. (They are not in clicks branch since I believe it is frozen for ota 12 release.)

Thanks!

[Ethan Chang (ethan.chang)]

Verified these 4 scopes on turbo.

[Kyle Nitzsche (knitzsche)]

Penk, I believe these four aggregator scopes were all released at high enough versions to fix this in ota13. Thus I will change to fix-reeased.

clicks branch ota13:
$ bzr ls -r tag:ota13 | grep dashboard_
com.canonical.scopes.dashboard_4.11.1_armhf.click
$ bzr ls -r tag:ota13 | grep nearby_
com.canonical.unity-scope-nearby_4.9.1_armhf.click
$ bzr ls -r tag:ota13 | grep "\.news_"
com.canonical.scopes.news_4.9.0_armhf.click
$ bzr ls -r tag:ota13 | grep "\.photos_"
com.canonical.scopes.photos_4.11.0_armhf.click