Source builds fail for packages with "3.0 (quilt)" format and unapplied patches

Source package build in Launchpad fails if the package has "3.0 (quilt)" format and some or all of the Quilt patches in it are not applied. The same recipe works for me locally in Precise's latest bzr-builder version 0.7.2-0ubuntu1

The errors are:
tar: recipe-<version_string>/.pc/<path_to_file>: Cannot open: Permission denied

Sample build log with the error can be found at https://launchpadlibrarian.net/125376199/buildlog.txt.gz

<dobey> in #launchpad suggests that this is "probably because dpkg-source isn't being run with fakeroot, and whatever applied the patches, was"

Workaround: Add "tar-ignore = .pc" to debian/source/options

Changing debian/source/format to "3.0 (native)" also fixes the source build but causes the patches to not be applied, which is obviously not the intended behavior.