git-version-gen: add --match argument

* build-aux/git-version-gen (Options): Add --match argument.
  (v_from_git): Remove path without --match.

build-aux/git-version-gen

@@ -1,6 +1,6 @@
 #!/bin/sh
 # Print a version string.
-scriptversion=2012-03-18.17; # UTC
+scriptversion=2012-07-06.14; # UTC
 
 # Copyright (C) 2007-2012 Free Software Foundation, Inc.
 #
@@ -85,20 +85,25 @@ Print a version string.
 
 Options:
 
-   --prefix           prefix of git tags (default 'v')
+   --prefix     prefix of git tags to strip from version (default 'v')
+   --match      pattern for git tags to match (default: '\$prefix*')
 
    --help       display this help and exit
    --version    output version information and exit
 
-Running without arguments will suffice in most cases."
+Running without arguments will suffice in most cases.  If no --match
+argument is given, only match tags that begin with the --prefix."
 
 prefix=v
+unset match
+unset tag_sed_script
 
 while test $# -gt 0; do
   case $1 in
     --help) echo "$usage"; exit 0;;
     --version) echo "$version"; exit 0;;
     --prefix) shift; prefix="$1";;
+    --match) shift; match="$1";;
     -*)
       echo "$0: Unknown option '$1'." >&2
       echo "$0: Try '--help' for more information." >&2
@@ -121,6 +126,7 @@ if test -z "$tarball_version_file"; then
     exit 1
 fi
 
+match="${match:-$prefix*}"
 tag_sed_script="${tag_sed_script:-s/x/x/}"
 
 nl='
@@ -151,8 +157,7 @@ then
 # directory, and "git describe" output looks sensible, use that to
 # derive a version string.
 elif test "`git log -1 --pretty=format:x . 2>&1`" = x \
-    && v=`git describe --abbrev=4 --match="$prefix*" HEAD 2>/dev/null \
-          || git describe --abbrev=4 HEAD 2>/dev/null` \
+    && v=`git describe --abbrev=4 --match="$match" HEAD 2>/dev/null` \
     && v=`printf '%s\n' "$v" | sed "$tag_sed_script"` \
     && case $v in
          $prefix[0-9]*) ;;