There are a few places in core that were preventing this from working by explicity setting `$wpdb->suppress_errors` to `false`. Instead, they should inherit the value that existed before errors were suppressed.
This allows Multisite unit tests to run without explosive database errors, and allows `$wpdb->suppress_errors` to be overridden all the way down the chain.
Fixes#26102.
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git-svn-id: http://core.svn.wordpress.org/trunk@26158 1a063a9b-81f0-0310-95a4-ce76da25c4cd