[PATCH 0/5] Use Xapian query syntax for batch-tag dump/restore

[Austin Clements]

This is a stab at tweaking the new batch-tag dump/restore format to be
more amenable to batch tagging.  Currently, the "query" part of each
line isn't really a Xapian query; it's a hex-encoded message ID
prefixed with "id:".  This is fine for the very limited case of
dump/restore, but it extends poorly to the general queries allowed by
batch tagging.  However, Xapian already has a perfectly good quoting
syntax.  This series switches the batch-tag format to use regular
Xapian queries, using only regular Xapian quoting syntax, so that we
don't have to invent yet another quoting syntax for batch tagging.