log_min_messages shows debug instead of debug2

Hi,

I noticed that if log_min_messages is set to ‘debug2’, it shows ‘debug’ instead of debug2.
Showing other debug options like debug1 work normally.
This is same for client_min_messages.

According to a033daf56 and baaad2330, debug is an alias for debug2 and for backward-compatibility.
And also these debug options are mainly used for PostgreSQL hackers, so I think this is a trivial issue.

Patch attached.
The output of ‘show log_min_messages’ becomes ‘debug2’ if it’s set to either debug or debug2.
It passed make installcheck.

I just changed the order of server_message_level_options[]
because in this case SHOW command linearly searches GUC option by config_enum_lookup_by_value().

What do you think about it?
If it’s worth committing, do I need test? I couldn’t find the relevant test set.

====================
Takeshi Ideriha
Fujitsu Limited