fix(__load_completion): do not warn when completing . first time

[scop]

ca361be enables warnings about trying to source directories when loading completions. That's useful, but triggers the errors in the common case of trying to source something, . Tab

Special case . (and for completeness, even though not that interesting, ..) so we don't issue the warning about them.

[akinomyoga]

I have a naive question. Do we need to output warnings here? Maybe we can just ignore the directories because the warning message disturbs the cursor positions in the terminal.

[scop]

#506 has the discussion related to this.

I'm not that concerned about messing with the output; this is a broken setup that should be fixed and not masked, consistent with what happens with a completion file with invalid syntax, or an unreadable one.

[akinomyoga]

Thank you for your explanation. Then, that's fine to keep the error message.

Maybe we can also explicitly mention in the error message that putting subdirectories in completions directories is the wrong setup?

[scop]

As mentioned in the commit message, the current warning mimics what bash itself would emit when sourcing a directory. If we keep it that way, there will be minimal behavioral changes ahead for users when the day comes we can drop our own -d check (probably when we start to require bash >= 4.3 -- would be good to find out the exact version in a comment here and document it, https://bugzilla.redhat.com/show_bug.cgi?id=903833)

[akinomyoga]

Thank you! I see the background! Please merge it as is.

[scop]

Done, along with 16ce83f documenting the bash version needing the check (verified locally, didn't bother to check 4.2.x patch versions).