Merge tag android-5.1.0_r1 into AOSP_5.1_MERGE

Change-Id: I2a5df3f506f7f4c113df4e4f1bb76adc631cd618
diff --git a/releasetools.py b/releasetools.py
index dba721e..26d9dcc 100644
--- a/releasetools.py
+++ b/releasetools.py
@@ -32,6 +32,10 @@
   else:
     WriteRadio(info, radio_img)
 
+def IncrementalOTA_InstallBegin(info):
+  info.script.Unmount("/system")
+  info.script.TunePartition("/system", "-O", "^has_journal")
+  info.script.Mount("/system")
 
 def IncrementalOTA_InstallEnd(info):
   try: