[Makefile] Introduce _ensure-current-version to ensure version tags

Makefile

@@ -55,6 +55,14 @@ ifndef TAG
 	$(error Please invoke with `make TAG=<new-version> release`, where <new-version> is either an increment specifier (patch, minor, major, prepatch, preminor, premajor, prerelease), or an explicit major.minor.patch version number)
 endif
 
+# Ensures there are version tags in repository
+.PHONY: _ensure-current-version
+
+_ensure-current-version:
+ifeq ($(shell git tag),$(printf ''))
+	@git fetch --tags
+endif
+
 # Ensures that the git workspace is clean.
 .PHONY: _ensure-clean
 _ensure-clean:
@@ -62,7 +70,7 @@ _ensure-clean:
 
 # Makes a release; invoke with `make TAG=<versionOrIncrementSpec> release`.
 .PHONY: release
-release: _ensure-tag _ensure-clean
+release: _ensure-tag _ensure-clean _ensure-current-version
 	@old_ver=`git describe --abbrev=0 --tags --match 'v[0-9]*.[0-9]*.[0-9]*'` || { echo "Failed to determine current version." >&2; exit 1; }; old_ver=$${old_ver#v}; \
 	 new_ver=`echo "$(TAG)" | sed 's/^v//'`; new_ver=$${new_ver:-patch}; \
 	 if printf "$$new_ver" | grep -q '^[0-9]'; then \