breaking change to bigquery

[Jonathan Amsterdam]

The Table.Update method now takes a third argument, an ETag.

Pass in the empty string to get the old behavior: the table's metadata is unconditionally changed.

If you're doing a read-modify-write, pass the ETag field from the TableMetadata you read. Then the Update will fail if the metadata has been modified since your read.  See the new example for details.

By the way, we've also added a Dataset.Update method.