tree fce75a143ba256058b510193584b414d230ae9f7
parent 9fe54061197c42faedc9417bdc70797681aa06d6
author Jonathan Nieder <jrn@google.com> 1596080450 -0700
committer Jonathan Nieder <jrn@google.com> 1596081132 -0700

Add support for tree filters when fetching

Teach the FilterSpec serialization code about tree filters so they can
be communicated over the wire and understood by the server.

While we're here, harden the FilterSpec serialization code to throw
IllegalStateException if we encounter a FilterSpec that cannot be
expressed as a "filter" line.  The only public API for creating a
Filterspec is to pass in a "filter" line to be parsed, so these should
not appear in practice.

Change-Id: I9664844059ffbc9c36eb829e2d860f198b9403a0
Signed-off-by: Jonathan Nieder <jrn@google.com>