I just installed the latest one-click installer on windows which comes
with irb with readline support.
And I stumbled onto the issue that now whenever you type '#' into irb
anywhere in the line, the whole line is then taken to be a comment and
irb proceeds to skip to the next line.
Obviously this is a problem with any string that wants to use ruby's
"#{var}" syntax.
Is this a known problem or normal behavior of irb/readline?  Or
something is broken with the latest one-click installer?  The problem
does not occur when irb is run without readline support.

For what it is worth, this is using a spanish keyboard, where the '#'
character is typed as "Alt Gr+3" (albeit the issue also happens when
cutting/pasting # from another application)