snap build job doesn't properly fail on incorrect shas of downloaded snaps

[anonymouse64]

See for example the log from this job:

22:26:13 �[91msha512sum: WARNING: 1 computed checksum did NOT match
22:26:13 �[0mcore.snap: FAILED
22:26:13 Parallel unsquashfs: Using 4 processors
22:26:13 �[91mRead on filesystem failed because EOF
22:26:13 read_uids_guids: failed to read id index table
22:26:13 FATAL ERROR:failed to uid/gid table
22:26:13 �[0mcore18.snap: OK

the job still goes on to try to run and fails for other unknown reasons.

[anonymouse64]

Probably somewhere in this block of code we are not failing on non-0 exit codes:

ci-management/shell/edgexfoundry-snapcraft.sh

Lines 134 to 148 in 7bf3d26

	RUN apt-get update && \
	apt-get dist-upgrade --yes && \
	apt-get install --yes \
	curl sudo jq squashfs-tools && \
	for thesnap in core core18 snapcraft; do \
	dlUrl=$(curl -s -H 'X-Ubuntu-Series: 16' -H "X-Ubuntu-Architecture: $ARCH" "https://api.snapcraft.io/api/v1/snaps/details/$thesnap" | jq '.download_url' -r); \
	dlSHA=$(curl -s -H 'X-Ubuntu-Series: 16' -H "X-Ubuntu-Architecture: $ARCH" "https://api.snapcraft.io/api/v1/snaps/details/$thesnap" | jq '.download_sha512' -r); \
	curl -s -L $dlUrl --output $thesnap.snap; \
	echo "$dlSHA $thesnap.snap" > $thesnap.snap.sha512; \
	sha512sum -c $thesnap.snap.sha512; \
	mkdir -p /snap/$thesnap && unsquashfs -n -d /snap/$thesnap/current $thesnap.snap && rm $thesnap.snap; \
	done && \
	apt remove --yes --purge curl jq squashfs-tools && \
	apt-get autoclean --yes && \
	apt-get clean --yes

probably just a set -e at the start would do the trick