diff --git a/pkt-line.c b/pkt-line.c
index 08a1427c0..62fdb3707 100644
--- a/pkt-line.c
+++ b/pkt-line.c
@@ -1,5 +1,6 @@
 #include "cache.h"
 #include "pkt-line.h"
+#include "run-command.h"
 
 char packet_buffer[LARGE_PACKET_MAX];
 static const char *packet_trace_prefix = "git";
@@ -11,6 +12,11 @@ void packet_trace_identity(const char *prog)
 	packet_trace_prefix = xstrdup(prog);
 }
 
+static const char *get_trace_prefix(void)
+{
+	return in_async() ? "sideband" : packet_trace_prefix;
+}
+
 static int packet_trace_pack(const char *buf, unsigned int len, int sideband)
 {
 	if (!sideband) {
@@ -57,7 +63,7 @@ static void packet_trace(const char *buf, unsigned int len, int write)
 	strbuf_init(&out, len+32);
 
 	strbuf_addf(&out, "packet: %12s%c ",
-		    packet_trace_prefix, write ? '>' : '<');
+		    get_trace_prefix(), write ? '>' : '<');
 
 	/* XXX we should really handle printable utf8 */
 	for (i = 0; i < len; i++) {
diff --git a/run-command.c b/run-command.c
index 3277cf797..c8029f239 100644
--- a/run-command.c
+++ b/run-command.c
@@ -595,7 +595,7 @@ static NORETURN void die_async(const char *err, va_list params)
 {
 	vreportf("fatal: ", err, params);
 
-	if (!pthread_equal(main_thread, pthread_self())) {
+	if (in_async()) {
 		struct async *async = pthread_getspecific(async_key);
 		if (async->proc_in >= 0)
 			close(async->proc_in);
@@ -614,6 +614,13 @@ static int async_die_is_recursing(void)
 	return ret != NULL;
 }
 
+int in_async(void)
+{
+	if (!main_thread_set)
+		return 0; /* no asyncs started yet */
+	return !pthread_equal(main_thread, pthread_self());
+}
+
 #else
 
 static struct {
@@ -653,6 +660,12 @@ int git_atexit(void (*handler)(void))
 }
 #define atexit git_atexit
 
+static int process_is_async;
+int in_async(void)
+{
+	return process_is_async;
+}
+
 #endif
 
 int start_async(struct async *async)
@@ -712,6 +725,7 @@ int start_async(struct async *async)
 		if (need_out)
 			close(fdout[0]);
 		git_atexit_clear();
+		process_is_async = 1;
 		exit(!!async->proc(proc_in, proc_out, async->data));
 	}
 
diff --git a/run-command.h b/run-command.h
index 5b4425a3c..629fab7ae 100644
--- a/run-command.h
+++ b/run-command.h
@@ -118,5 +118,6 @@ struct async {
 
 int start_async(struct async *async);
 int finish_async(struct async *async);
+int in_async(void);
 
 #endif