avoid --exclude with git-describe

The `--exclude` flag is not supported by older-but-still-used version
of Git.

original commit: a5a594f7c3f71d17d2e55ed50463b92515de02dc

s/update-revision

@@ -1,6 +1,6 @@
 #!/bin/sh
 if [ -d ../../.git ]; then
-  git describe --always --exclude='*' --abbrev=40 --dirty
+  git describe --always --match='' --abbrev=40 --dirty
   echo 'git'
 elif [ -d ../../.hg ]; then
   DIRTY="$(hg status -n --color never --pager never | head -1)"