Fix logic for finding the beta version number

* autogen.sh: Check if $tmp is empty after each assignment.
--

This fixes the problem that due to the gpg4win-5.0.0-beta103 tag
`./autogen.sh --find-version gpg4win 5 0 0` erroneously outputs
version 5.0.0 instead of 5.0.0-betaNNN.

Fix originally done for gpg4win and copied to gpgrt by [email protected]:
  commit d3452493e665a4175218b7272ca8b1ca6fc57718
  Author:     Ingo Klöcker <[email protected]>
  AuthorDate: Wed Feb 19 15:46:55 2025 +0100

1 files changed, 5 insertions, 3 deletions

diff --git a/autogen.sh b/autogen.sh
index 0b08e8b..a2c469f 100755
--- a/autogen.sh
+++ b/autogen.sh
@@ -15,7 +15,7 @@
 # configure it for the respective package.  It is maintained as part of
 # GnuPG and source copied by other packages.
 #
-# Version: 2024-12-03
+# Version: 2025-02-21
 
 configure_ac="configure.ac"
 
@@ -264,13 +264,15 @@ if [ "$myhost" = "find-version" ]; then
       if [ -n "$tmp" ]; then
           tmp=$(echo "$tmp" | sed s/^"$package"// \
                     | awk -F- '$3!=0 && $3 !~ /^beta/ {print"-beta"$3}')
-      else
+      fi
+      if [ -z "$tmp" ]; then
           # (due tof "-base" in the tag we need to take the 4th field)
           tmp=$(git describe --match "${matchstr2}" --long 2>/dev/null)
           if [ -n "$tmp" ]; then
               tmp=$(echo "$tmp" | sed s/^"$package"// \
                         | awk -F- '$4!=0 && $4 !~ /^beta/ {print"-beta"$4}')
-          elif [ -n "${matchstr3}" ]; then
+          fi
+          if [ -z "$tmp" -a -n "${matchstr3}" ]; then
               tmp=$(git describe --match "${matchstr3}" --long 2>/dev/null)
               if [ -n "$tmp" ]; then
                   tmp=$(echo "$tmp" | sed s/^"$package"// \