qemu detection: Free up previous qemu help/version strings if they exist.

diff --git a/src/launch.c b/src/launch.c
index db76885..cb0f637 100644 (file)
--- a/src/launch.c
+++ b/src/launch.c
@@ -1071,6 +1071,11 @@ test_qemu (guestfs_h *g)
   char cmd[1024];
   FILE *fp;
 
+  free (g->qemu_help);
+  g->qemu_help = NULL;
+  free (g->qemu_version);
+  g->qemu_version = NULL;
+
   snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -nographic -help", g->qemu);
 
   /* qemu -help should always work (qemu -version OTOH wasn't