Dump fingerprints into recovery log

No more guessing. We should have the info for OTA issues diagnosis.

Change-Id: I0ce919434444ab16a38cc7af818e64785509b0fb
diff --git a/tools/releasetools/ota_from_target_files.py b/tools/releasetools/ota_from_target_files.py
index 26fbaf0..21565fc 100755
--- a/tools/releasetools/ota_from_target_files.py
+++ b/tools/releasetools/ota_from_target_files.py
@@ -556,6 +556,10 @@
 else if get_stage("%(bcb_dev)s") == "3/3" then
 """ % bcb_dev)
 
+  # Dump fingerprints
+  script.Print("Target: %s" % CalculateFingerprint(
+      oem_props, oem_dict, OPTIONS.info_dict))
+
   device_specific.FullOTA_InstallBegin()
 
   system_progress = 0.75
@@ -731,6 +735,12 @@
       metadata=metadata,
       info_dict=OPTIONS.info_dict)
 
+  # TODO: Currently this works differently from WriteIncrementalOTAPackage().
+  # This function doesn't consider thumbprints when writing
+  # metadata["pre/post-build"]. One possible reason is that the current
+  # devices with thumbprints are all using file-based OTAs. Long term we
+  # should factor out the common parts into a shared one to avoid further
+  # divergence.
   source_fp = GetBuildProp("ro.build.fingerprint", OPTIONS.source_info_dict)
   target_fp = GetBuildProp("ro.build.fingerprint", OPTIONS.target_info_dict)
   metadata["pre-build"] = source_fp
@@ -828,6 +838,12 @@
 else if get_stage("%(bcb_dev)s") != "3/3" then
 """ % bcb_dev)
 
+  # Dump fingerprints
+  script.Print("Source: %s" % CalculateFingerprint(
+      oem_props, oem_dict, OPTIONS.source_info_dict))
+  script.Print("Target: %s" % CalculateFingerprint(
+      oem_props, oem_dict, OPTIONS.target_info_dict))
+
   script.Print("Verifying current system...")
 
   device_specific.IncrementalOTA_VerifyBegin()
@@ -1206,6 +1222,10 @@
 else if get_stage("%(bcb_dev)s") != "3/3" then
 """ % bcb_dev)
 
+  # Dump fingerprints
+  script.Print("Source: %s" % (source_fp,))
+  script.Print("Target: %s" % (target_fp,))
+
   script.Print("Verifying current system...")
 
   device_specific.IncrementalOTA_VerifyBegin()