Off topic: help with CVS, please!

[Alan Mackenzie <acm@muc.de>]

Hi, Emacs!

Could somebody help me with CVS, please.

I've got the CC Mode repository into a mess.  The head of cc-langs.el is
5.288, and contains crud.  I want to (somehow) get 5.286 and (somehow)
commit it, so that it becomes head.

I tried deleting cc-langs.el and
    # cvs update -r5.286 cc-langs.el
An immediate "cvs update" then failed, without contacting the server or
giving an error message.

I then tried something or other (can't remember exactly what), but
managed to damage CVS/Entries.  Then I tried to download 5.286 to
standard output.  There doesn't seem to be a nice
simple command like
    # cvs get -r5.286 cc-langs.el > /path/to/temp_file.el
, which would just get a file version without having to worry about
fouling anything up.

There's something similar which I tried, namely:
    # cvs update -p r5.286 cc-langs.el > /path/to/temp_file.el,
but I'm not convinced I got 5.286, and I'm now too frustrated and
confused to check reliably.

Could somebody with a clear head please suggest a recipe to me for
obtaining 5.286 and committing it, unchanged, over 5.288 to become the
new head.

Thanks in advance!

-- 
Alan Mackenzie (Nuremberg, Germany).