Use a new package version scheme

If available, the Git repository description is used as package
version. Otherwise, the version provided by Autoconf is used. The scheme
for release versions remains the same.

m4/swodec.m4

@@ -24,22 +24,14 @@
 m4_define([_SWODEC_SET_PACKAGE_VERSION], [
 	m4_assert([$# == 5])
 
-	# Get the short Git revision hash of the current commit.
-	git_version=`git --git-dir="$srcdir/.git" rev-parse \
-		--short HEAD 2> /dev/null`
-
-	# Try to get the release tag for the package version from the current
-	# commit.
-	tag=`git --git-dir="$srcdir/.git" describe --match "$2" \
-		--exact-match 2> /dev/null`
-
-	version=$2
-
-	# If Git is available, append the short Git revision hash of the
-	# current commit to the version string if there is no release tag for
-	# the package version on it.
-	AS_IF([test -n "$git_version" && test -z "$tag"],
-		[version="$version-git-$git_version"])
+	# Get the Git repository description. Ensure that we use our Git
+	# repository even when there is a parent Git repository.
+	git_version=`git -C "$srcdir" --git-dir=.git describe --dirty 2> /dev/null`
+
+	# If available, use the Git description as package version. Otherwise,
+	# use the version provided by Autoconf.
+	AS_IF([test -n "$git_version"], [version="$git_version"],
+		[version="$2"])
 
 	AC_SUBST([$1_MAJOR], [$3])
 	AC_SUBST([$1_MINOR], [$4])