release: Stop suppressing errors from VM image creation scripts

[markj]

Summary

In the spirit of commit 611c1457ff32 ("release: Add set -e to abort upon failure")
we should avoid this kind of blanket error suppression.

Note, there are still some uses of this pattern, e.g., in the main
release Makefile when it installs packages. In those cases it is less
clear to me whether the pattern should be removed.

[cperciva]

If we don't have this, cloudware image failing to build results in the entire weekly snapshot dying. I don't want to not have a weekly snapshot just because the Azure port is broken.

[lwhsu]

Maybe make it optional and can be set in the config so we have "develop" and "release" modes?

[markj]

In D51882#1185710, @cperciva wrote:

If we don't have this, cloudware image failing to build results in the entire weekly snapshot dying. I don't want to not have a weekly snapshot just because the Azure port is broken.

Sorry, I should have looked more closely at the git blame output.

[cperciva]

In D51882#1186279, @markj wrote:

Sorry, I should have looked more closely at the git blame output.

No worries! Thanks for asking for review first. :-)

[jrtc27]

In D51882#1185733, @lwhsu wrote:

Maybe make it optional and can be set in the config so we have "develop" and "release" modes?

I do like this idea, though as a make -DFOO, that the snapshot builds can opt into. Unconditionally and silently squashing errors in creating some of the images isn't great practice.