Merge "Partially revert BUILD_DATETIME change"
diff --git a/core/version_defaults.mk b/core/version_defaults.mk
index 9f76bc8..858384b 100644
--- a/core/version_defaults.mk
+++ b/core/version_defaults.mk
@@ -254,12 +254,23 @@
BUILD_ID := UNKNOWN
endif
-ifneq (,$(findstring Darwin,$(UNAME)))
-DATE := date -r $(shell cat $(BUILD_DATETIME_FILE))
-else
-DATE := date -d @$(shell cat $(BUILD_DATETIME_FILE))
+ifndef BUILD_DATETIME
+ # Used to reproduce builds by setting the same time. Must be the number
+ # of seconds since the Epoch.
+ BUILD_DATETIME := $(shell date +%s)
endif
+ifneq (,$(findstring Darwin,$(UNAME)))
+DATE := date -r $(BUILD_DATETIME)
+else
+DATE := date -d @$(BUILD_DATETIME)
+endif
+
+# Everything should be using BUILD_DATETIME_FROM_FILE instead.
+# BUILD_DATETIME and DATE can be removed once BUILD_NUMBER moves
+# to soong_ui.
+BUILD_DATETIME :=
+
ifndef BUILD_NUMBER
# BUILD_NUMBER should be set to the source control value that
# represents the current state of the source code. E.g., a