Omit leading 'v' from python .tar.gz revision

Signed-off-by: Brenden Blanco <bblanco@plumgrid.com>

scripts/CMakeLists.txt

@@ -5,7 +5,7 @@ string(SUBSTRING "${GIT_SHA1}" 0 8 GIT_SHA1_SHORT)
 git_describe(GIT_DESCRIPTION)
 git_describe(GIT_TAG_LAST "--abbrev=0")
 git_get_exact_tag(GIT_TAG_EXACT)
-set(REVISION "${GIT_TAG_LAST}-${GIT_SHA1_SHORT}")
+string(SUBSTRING "${GIT_TAG_LAST}-${GIT_SHA1_SHORT}" 1 -1 REVISION)
 if(GIT_TAG_EXACT)
   string(SUBSTRING "${GIT_TAG_EXACT}" 1 -1 REVISION)
   message(STATUS "Currently on Git tag ${GIT_TAG_EXACT}")