v2017.03 no longer exists and produces warnings if set as preferred:
NOTE: Resolving any missing task queue dependencies
NOTE: preferred version v2017.03% of u-boot not available (for item virtual/bootloader)
NOTE: versions of u-boot available: 1:2018.01 2:v2018.03+gitAUTOINC+f95ab1fb6e
NOTE: preferred version v2017.03% of u-boot not available (for item u-boot-dev)
NOTE: versions of u-boot available: 1:2018.01 2:v2018.03+gitAUTOINC+f95ab1fb6e
NOTE: preferred version v2017.03% of u-boot not available (for item u-boot)
NOTE: versions of u-boot available: 1:2018.01 2:v2018.03+gitAUTOINC+f95ab1fb6e
Signed-off-by: Mirza Krak <mirza.krak@northern.tech>