+# If it's not already specified, derive the GPG key ID from
+# the signed tag we've just applied to mark this release.
+gpg_key_ID ?= \
+ $$(git cat-file tag v$(VERSION) > .ann-sig \
+ && gpgv .ann-sig - < /dev/null 2>&1 \
+ | sed -n '/.*key ID \([0-9A-F]*\)/s//\1/p'; rm -f .ann-sig)
+