Check for Empty Safe-Update file

[borpin]

EmonScripts/update/service-runner-update.sh

Line 36 in f07850a

save_to_update=$(curl -s https://raw.githubusercontent.com/openenergymonitor/EmonScripts/master/safe-update)

If an empty file is returned by the CRUL command, the error given to the user is that the image is too old rather than there was an error checking the safe-update.

Suggest the CURL tries a couple of times.

[borpin]

Fixed

EmonScripts/update/service-runner-update.sh

Line 49 in 1e93b91

while [ $retry -lt 5 ]; do