build: allow defined but empty FLB_NIGHTLY_BUILD
@@ -210,7 +210,7 @@ option(FLB_FILTER_RECORD_MODIFIER "Enable record_modifier filter" Yes)
option(FLB_FILTER_TENSORFLOW "Enable tensorflow filter" No)
option(FLB_FILTER_GEOIP2 "Enable geoip2 filter" Yes)
-if(DEFINED FLB_NIGHTLY_BUILD)
+if(DEFINED FLB_NIGHTLY_BUILD AND NOT "${FLB_NIGHTLY_BUILD}" STREQUAL "")
FLB_DEFINITION_VAL(FLB_NIGHTLY_BUILD ${FLB_NIGHTLY_BUILD})
endif()
