peel_ref: do not return a null sha1

diff --git a/advice.c b/advice.c
index a492eea24f71ad2d2082efce9d1d925a5766b111..edfbd4a6fb01a6905671d6d842d22c4869fad729 100644 (file)
--- a/advice.c
+++ b/advice.c
@@ -32,7 +32,7 @@ void advise(const char *advice, ...)
        const char *cp, *np;
 
        va_start(params, advice);
-       strbuf_addf(&buf, advice, params);
+       strbuf_vaddf(&buf, advice, params);
        va_end(params);
 
        for (cp = buf.buf; *cp; cp = np) {