delta-find: use "-1" as depth snapshot-dept for non snapshot in debug

This will help do distinct full snapshot (level 0) and normal delta (not a snapshot, no snapshot level)

mercurial/revlogutils/deltas.py

@@ -1411,7 +1411,7 b' class deltacomputer:'
                     dbg['delta_try_count'] = 0
                     dbg['type'] = b"full"
                     if snapshotdepth is None:
-                        dbg['snapshot-depth'] = 0
+                        dbg['snapshot-depth'] = -1
                     else:
                         dbg['snapshot-depth'] = snapshotdepth
                     self._dbg_process_data(dbg)
@@ -1582,7 +1582,7 b' class deltacomputer:'
                     'snapshot-depth'
                 ] = deltainfo.snapshotdepth  # pytype: disable=attribute-error
             else:
-                dbg['snapshot-depth'] = 0
+                dbg['snapshot-depth'] = -1
             self._dbg_process_data(dbg)
         return deltainfo
 

tests/test-bundle.t

@@ -1062,8 +1062,8 b' Test the debug output when applying delt'
   DBG-DELTAS: CHANGELOG:   rev=2: delta-base=2 is-cached=1 - search-rounds=0 try-count=0 - delta-type=full   snap-depth=0 - p1-chain-length=0 p2-chain-length=-1 - duration=* (glob)
   adding manifests
   DBG-DELTAS: MANIFESTLOG: rev=0: delta-base=0 is-cached=1 - search-rounds=0 try-count=0 - delta-type=full   snap-depth=0 - p1-chain-length=-1 p2-chain-length=-1 - duration=* (glob)
-  DBG-DELTAS: MANIFESTLOG: rev=1: delta-base=0 is-cached=1 - search-rounds=1 try-count=1 - delta-type=delta  snap-depth=0 - p1-chain-length=0 p2-chain-length=-1 - duration=* (glob)
-  DBG-DELTAS: MANIFESTLOG: rev=2: delta-base=1 is-cached=1 - search-rounds=1 try-count=1 - delta-type=delta  snap-depth=0 - p1-chain-length=1 p2-chain-length=-1 - duration=* (glob)
+  DBG-DELTAS: MANIFESTLOG: rev=1: delta-base=0 is-cached=1 - search-rounds=1 try-count=1 - delta-type=delta  snap-depth=-1 - p1-chain-length=0 p2-chain-length=-1 - duration=* (glob)
+  DBG-DELTAS: MANIFESTLOG: rev=2: delta-base=1 is-cached=1 - search-rounds=1 try-count=1 - delta-type=delta  snap-depth=-1 - p1-chain-length=1 p2-chain-length=-1 - duration=* (glob)
   adding file changes
   DBG-DELTAS: FILELOG:a:   rev=0: delta-base=0 is-cached=1 - search-rounds=0 try-count=0 - delta-type=full   snap-depth=0 - p1-chain-length=-1 p2-chain-length=-1 - duration=* (glob)
   DBG-DELTAS: FILELOG:b:   rev=0: delta-base=0 is-cached=1 - search-rounds=0 try-count=0 - delta-type=full   snap-depth=0 - p1-chain-length=-1 p2-chain-length=-1 - duration=* (glob)