Comment 1:

QueryEscape escape the query part of the URL,
and a space in query is escaped as +.

Status changed to WorkingAsIntended.

Comment 2:

Is that actually specified somewhere?
net/url assumes a query parameter to follow application/x-www-form-urlencoded rules
instead of RFC's.
RFC1738 defines + as an allowed character but doesn't specify it to be a space, even
though it is commonly regarded as such.
RFC3986 seems to recommend %20 for spaces.
net/url makes a special case out of the space, even though url.go refers to RFC3986.
If I recall correctly the + sign is used when a browser submits a form to an url, for
legacy reasons(?) when using mime-type 'application/x-www-form-urlencoded'.
This is, however, not part of an RFC?
So both forms are in use and both appear to be syntactically correct (even though using
the + sign is older but more readable), so when encoding one just has to choose.
See also:
http://en.wikipedia.org/wiki/Percent-encoding#The_application.2Fx-www-form-urlencoded_type

Comment 3 by psnim2000:

It seems that the query portion can be escaped as "%20" or "+" and the path portion can
only be escaped as "%20".
I was using this function to generate paths and because "+" did not become spaces,
according the browser, there was an unintended consequence.
It seems to me it would be better to have it encode to "%20" as they work for both cases.

API for proper percent-encoding would be still nice to have.