Add support for 'T' transition snapshots, which are identical to S snapshots except they tell the makefile to stop at stage1.

src/etc/get-snapshot.py

@@ -41,9 +41,6 @@ def determine_curr_snapshot_for_platform():
     parsed = parse_line(i, line)
     if (not parsed): continue
 
-    if parsed["type"] == "transition":
-      raise Exception("working on a transition, not updating stage0")
-
     if found_snap and parsed["type"] == "file":
       if parsed["platform"] == platform:
         hsh = parsed["hash"]

src/etc/snapshot.py

@@ -35,10 +35,7 @@ def parse_line(n, line):
   match = re.match(r"([ST]) (\d{4}-\d{2}-\d{2}) ([a-fA-F\d]+)\s*$", line);
   if (not match):
     raise Exception("%s:%d:E syntax error" % (snapshotfile, n))
-  ttype = "snapshot"
-  if (match.group(1) == "T"):
-    ttype = "transition"
-  return {"type": ttype,
+  return {"type": "snapshot",
           "date": match.group(2),
           "rev": match.group(3)}