test-flagprocessor: use changegroup3 in bundle2

This will force "hg bundle" to use changegroup3 in the test. It is
important since only changegroup3 preserves revlog flags.

tests/flagprocessorext.py

@@ -7,6 +7,7 b' import zlib'
 
 from mercurial import (
     changegroup,
+    exchange,
     extensions,
     filelog,
     revlog,
@@ -103,6 +104,10 b' def extsetup(ui):'
     revlog.REVIDX_KNOWN_FLAGS |= util.bitsfrom(flags)
     revlog.REVIDX_FLAGS_ORDER.extend(flags)
 
+    # Teach exchange to use changegroup 3
+    for k in exchange._bundlespeccgversions.keys():
+        exchange._bundlespeccgversions[k] = '03'
+
     # Add wrappers for addrevision, responsible to set flags depending on the
     # revision data contents.
     wrapfunction(filelog.filelog, 'addrevision', noopaddrevision)