minor \markup (with variables) bug

[Graham Percival]

When using a variable (or macro?) in markup, there's an extra
space at the end of the string.  In the three lines below, the middle
line has an extra space (FOO_.) between the FOO and the period.

%%  Fink 2.7.3
\version "2.6.0"
\header{
var = "FOO"

tagline = \markup{ \center-align {
  \line {FOO.}
  \line {\var.}
  \line {\var \hspace #-1.0 .}
  }}
}
{c'4}