Unset BUILD_NUMBER/HOSTNAME in kati.go

BUILD_NUMBER/HOSTNAME is passed by a file, not env variable.
To avoid kati recreation, unset BUILD_NUMBER/HOSTNAME after
writing it into a file

Bug: 278060169
Test: BUILD_NUMBER=1 m && BUILD_NUMBER=2 m (check there is no kati
re-run)

Change-Id: I5a31461dcf1e4b0634974bcb48a0d7482d42852a
diff --git a/ui/build/kati.go b/ui/build/kati.go
index 4297378..aea56d3 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -188,13 +188,14 @@
 	}
 
 	hostname, ok := cmd.Environment.Get("BUILD_HOSTNAME")
+	// Unset BUILD_HOSTNAME during kati run to avoid kati rerun, kati will use BUILD_HOSTNAME from a file.
+	cmd.Environment.Unset("BUILD_HOSTNAME")
 	if !ok {
 		hostname, err = os.Hostname()
 		if err != nil {
 			ctx.Println("Failed to read hostname:", err)
 			hostname = "unknown"
 		}
-		cmd.Environment.Set("BUILD_HOSTNAME", hostname)
 	}
 	writeValueIfChanged(ctx, config, config.SoongOutDir(), "build_hostname.txt", hostname)
 
@@ -209,6 +210,8 @@
 	// anyone trying to parse it as an integer will probably get "0".
 	cmd.Environment.Unset("HAS_BUILD_NUMBER")
 	buildNumber, ok := cmd.Environment.Get("BUILD_NUMBER")
+	// Unset BUILD_NUMBER during kati run to avoid kati rerun, kati will use BUILD_NUMBER from a file.
+	cmd.Environment.Unset("BUILD_NUMBER")
 	if ok {
 		cmd.Environment.Set("HAS_BUILD_NUMBER", "true")
 		writeValueIfChanged(ctx, config, config.OutDir(), "file_name_tag.txt", buildNumber)