Fix beta version suffix

Makefile

@@ -3,7 +3,7 @@ LAST_TAG := $(shell git describe --tags --abbrev=0)
 COMMITS := $(shell echo `git log --oneline $(LAST_TAG)..HEAD | wc -l`)
 VERSION := $(shell cat VERSION)
-ifneq ($(VERSION),$(LAST_TAG))
+ifneq (v$(VERSION),$(LAST_TAG))
     VERSION := $(shell echo $(VERSION)~beta.$(COMMITS).g$(REVISION))
 endif