config: Keep inner whitespace verbatim

config: Keep inner whitespace verbatim

Configuration values are expected to be quoted when they have leading or
trailing whitespace, but inner whitespace should be kept verbatim even if
the value is not quoted. This is already documented in git-config(1), but
the code caused inner whitespace to be collapsed to a single space,
breaking, for example, clones from a path that has two consecutive spaces
in it, as future fetches would only see a single space.

Reported-by: John te Bokkel <tanj.tanj@gmail.com>
Signed-off-by: Björn Steinbrink <B.Steinbrink@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>