git-extra: fix the pkgver logic again

In 48e2403 (git-extra: ignore generated changes for the sake of
`pkgver`, 2025-03-05) I tried to address the fact that the commit that
updates `pkgver` in `PKGBUILD` necessarily touches the `git-extra/`
subdirectory, yet should not be considered for the package version.

What I failed to address is the rare case when `HEAD` is not the same as
`$rev`, i.e. when the last commit that touched the `git-extra/`
directory` is not at the tip of the branch.

Let's accommodate for that, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

git-extra/PKGBUILD

@@ -20,9 +20,11 @@ pkgver() {
   cd "$startdir"
   test ! -f "$(git rev-parse --git-path shallow)" || git -c http.sslbackend fetch --unshallow
   rev="$(git rev-list -1 HEAD -- . ':(exclude)./git-extra.install')"
-  test -n "$(git show . ':(exclude)./git-extra.install' |
-    sed -n -e '1,/^@@/d' -e '/^[-+]pkgver=/d' -e '/^[-+]pkgver=/d' -e "/^[-+] *'[0-9a-f]\{64\}'$/d" -e '/^[-+]/p')" ||
-  rev="$(git rev-list -1 $rev^ -- .)"
+  while test -z "$(git show $rev . ':(exclude)./git-extra.install' |
+    sed -n -e '1,/^@@/d' -e '/^[-+]pkgver=/d' -e '/^[-+]pkgver=/d' -e "/^[-+] *'[0-9a-f]\{64\}'$/d" -e '/^[-+]/p')"
+  do
+    rev="$(git rev-list -1 $rev^ -- .)"
+  done
   printf "%s.%s.%s" "${_ver_base}" "$(git rev-list --count $rev -- .)" \
     "$(git rev-parse --short=9 $rev)"
 }