Given the following secrets.yml:

common:
    FOO: foo

production:
    BAR: bar

Here is some observed behavior:

$ summon -e production printenv | egrep 'FOO|BAR'
BAR=bar
FOO=foo
$ summon -e common printenv | egrep 'FOO|BAR'
FOO=foo
$ summon printenv | egrep 'FOO|BAR'
$

The first two observations match my expectations based on the documentation.

The third example's behavior isn't mentioned in the documentation, so I won't go so far as to call it a bug.

However, it is mildly surprising. Since common is always inherited by other sections, I kinda had a weak expectation that its values would always get injected, even if we do not pass -e on the command line.

Docs should be elaborated with examples to describe the behavior in more details between root vars and common section as it changes when using and omitting the -e variable.