link to a tag rather than a branch for reproducability

diff --git a/openpower/sv/twin_butterfly.mdwn b/openpower/sv/twin_butterfly.mdwn
index f531615a0e7f06fb1b8edd2d981e6d3767c6756a..f700e21a0af65f3dbfefe31f9a4d6f270bbf20f0 100644 (file)
--- a/openpower/sv/twin_butterfly.mdwn
+++ b/openpower/sv/twin_butterfly.mdwn
@@ -57,7 +57,7 @@ one would just have to call the same instruction with different order a,
 b and a different constant c.
 
 Example taken from libvpx
-<https://chromium.googlesource.com/webm/libvpx/+/refs/heads/main/vpx_dsp/fwd_txfm.c#132>:
+<https://chromium.googlesource.com/webm/libvpx/+/refs/tags/v1.13.0/vpx_dsp/fwd_txfm.c#132>:
 
 ```
     #include <stdint.h>