From what I remember it will not show you an update at all. It will stay on the version you have installed.
But I would have to check to be sure

Thanks for checking Thomas. That is what I would have expected but I wouldn't have expected that rather scary "You are not connected..." message - is that right?

I just checked and it's indeed the case. You will be disconnected from an update stream, essentially disabling the Joomla Update component and you will not get any update at all for Joomla as long as you have that setting selected.

So the message in fact should be even more scary
You should only choose this if the server runs on an isolated network where it couldn't connect to the update stream anyway. Other than that I don't see any reason for that setting.

I still say everyone's trying to force the option to do something it wasn't designed to do. If you read the code from the first release it was included (2.5.4), the method applyUpdateSite method specifically checked for this "nochange" option and by the way the code reads, made zero changes to the update site configuration. Apparently that wasn't clear enough as in current staging the method resets the update site option. But, that's a choice other people seem to agree with so I'll butt out from here; my main point is that option's being screwed around with in ways it wasn't intended to be.

But it says (no change) yet change does happen. It doesn't leave me in the state I arrived in eg in my case, on the test server. So when/why would that option be used? The message perhaps should be changed to describe that use?

...and if it is just a 'don't change what I am using at the moment' choice, what is the point when there is the usual save button available at the top.

Considering it is pointing to an update server, it should have been 'None'. Meaning it shouldn't use any update server. Which results in not checking whether there are updates.

The update option "Currently configured (no change)" shoud have been removed with the merge of PR #5547 in current staging, or not?

No, it is not removed. The functionality was changed and for some strange reason accepted!

So are this issue options? :

1. Leave "Currently configured (no change)" as a server option but make the label more understandable and the view that follows more explanatory. (At the moment it makes no sense and giving a warning after a completed action doesn't seem correct - see screen shot above).

2. Remove this option as (no change) is incorrect and a normal user wouldn't understand it or use it. (I am assuming that if it is no longer an option it won't make a difference and really isn't required to work eg offline).

Apparently the option was deleted and the behavior for its saved value
changed for reasons beyond my understanding. Right or wrong, the text for
the option and the use I demonstrated in the code shows exactly what that
option should have done; made no changes whatsoever. Apparently the option
was disabling the update system completely. So instead of fixing that bug,
we just remove the option completely and make a B/C breaking change to the
value's handling that forces Joomla to make a change to the update URL.
shrug this is why I try to not make decisions on PRs anymore

On Sunday, January 4, 2015, Hils notifications@github.com wrote:

So are this issue options? :

1.

Leave "Currently configured (no change)" as a server option but make
the label more understandable and the view that follows more explanatory.
(At the moment it makes no sense and giving a warning after a completed
action doesn't seem correct - see screen shot above).
2.

Remove this option as (no change) is incorrect and a normal user
wouldn't understand it or use it. (I am assuming that if it is no longer an
option it won't make a difference and really isn't required to work eg
offline).

—
Reply to this email directly or view it on GitHub
#5614 (comment).

So is it wrong? Looks like people agree it is! So we need a decision as to what happens now - nothing or 1 or 2 or something else?

the code shows exactly what that option should have done; made no changes whatsoever

I never really understood the purpose of the option myself. Imho disabling the Joomla Updater makes most sense to me.
Why would we need an option to make no changes when the user as well just can click the cancel button of the form? But then, we have a lot of funny code in our CMS

+1 @Bakual
anyone for a patch?

I still do not understand what you are talking about.
After a clean install of latest staging there is no option value "Currently configured (no change)":

Any previously adjusted value different to the available values will be set to "Default" when upgrading a Joomla <= 3.3.6.
So what do we need a patch for?
This issue here is obsolete, or I do not understand something wrong?

You are right. My testing server was outdated, probably because our master is behind (Jenkins is broken atm). Once updated to staging, the issue no longer exists.

oops. closing now.

Excellent - thank you everyone :)