arch-all PPA packages create publications for non-PPA-supported architectures

unexpected architecture for arch-all binary packages reported by getPublishedBinaries() for non-native PPAs.

in the following example, i browse chromium-daily/beta and look for chromium-browser-inspector which is arch-all.

>>> user=lp.people['chromium-daily']
>>> ppa=user.ppas[0]
>>> ppa
<archive at https://api.edge.launchpad.net/1.0/~chromium-daily/+archive/beta>
>>> srcs = ppa.getPublishedSources(status = 'Published')
>>> src = srcs[0]
>>> src
<source_package_publishing_history at https://api.edge.launchpad.net/1.0/~chromium-daily/+archive/beta/+sourcepub/1297030>
>>> bins = src.getPublishedBinaries(binary_name = 'chromium-browser-inspector')
Traceback (most recent call last):
...
ValueError: Unrecognized parameter(s): 'binary_name' <==== *sigh*
>>> bins = src.getPublishedBinaries()
>>> bins[0].binary_package_name
u'chromium-browser'
>>> bins[1].binary_package_name
u'chromium-browser'
>>> bins[2].binary_package_name
u'chromium-browser-dbg'
>>> bins[3].binary_package_name
u'chromium-browser-dbg'
>>> bins[4].binary_package_name
u'chromium-browser-inspector'
>>> bins[4].distro_arch_series.architecture_tag
'amd64'
>>> bins[5].binary_package_name
u'chromium-browser-inspector'
>>> bins[5].distro_arch_series.architecture_tag
'armel' <===== bingo!

none of the chromium-daily PPAs are native so they only have access to i386/amd64/lpia builders, hence, they should not report builds for armel, powerpc, etc, yet they do for arch-all binaries.