mailfs: handle NIL body
diff --git a/src/cmd/upas/nfs/imap.c b/src/cmd/upas/nfs/imap.c
index e81ab27..e1a7777 100644
--- a/src/cmd/upas/nfs/imap.c
+++ b/src/cmd/upas/nfs/imap.c
@@ -1416,6 +1416,8 @@
 {
 	char *p;
 	
+	if(isnil(v))
+		return estrdup("");
 	p = v->data;
 	v->data = nil;
 	return p;