Before this change, since `undefined' is encoded as `null' when serialized,
there was no way for the server to disambiguate between unmodified values
and a truncation point. For example:
[ undefined, undefined, null, null, null ]
The above array represents two unmodified and three removed indexes. But
this is serialzed into JSON as:
[ null, null, null, null, null ]
It isn't possible for the server to determine what the truncation point is
from that diff. The solution is to therefore truncate the array _before_
sending it to the server, providing a trailing null to indicate that a
truncation has occurred:
[ null, null, null ]
The above means that the first two indexes are unmodified, and that index 2
and later should all be truncated.
* doc/client.texi (Saving to Server): New section.
* src/client/transport/XhttpQuoteTransport.js (_truncateDiff): New method to
perform truncation.
(getBucketDataJson): Use it.
* test/client/transport/XhttpQuoteTransportTest.js: New file with respective
test case.
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