The pre-install operations may fail, yet that failure is not
elevated to the user. This masks the failure and makes early
package install issues difficult to troubleshoot.
If the basic pre-install script fails, the charm should not
proceed to later hooks as the requirements may not be met.
Hashbangs for bash should specify -e (errexit) on all of the
pre-install bash scripts.
Change-Id: I40fedc011933cbce6215dd124019d251b6dafd61
Closes-bug: #1815243
Partial-bug: #1815231
058cd81d40