error plotting "single" values

[Francesco Potorti`]

octave> plot(single(1:2))
error: invalid value for array property "ydata"
error: set: expecting argument 4 to be a property name
error: set: expecting argument 6 to be a property name
error: set: expecting argument 8 to be a property name
error: set: expecting argument 10 to be a property name
error: called from:
error:   /usr/share/octave/3.1.54/m/plot/__line__.m at line 65, column 5
error:   /usr/share/octave/3.1.54/m/plot/line.m at line 38, column 5
error:   /usr/share/octave/3.1.54/m/plot/__plt2vv__.m at line 72, column 12
error:   /usr/share/octave/3.1.54/m/plot/__plt2__.m at line 68, column 14
error:   /usr/share/octave/3.1.54/m/plot/__plt1__.m at line 61, column 10
error:   /usr/share/octave/3.1.54/m/plot/__plt__.m at line 83, column 10
error:   /usr/share/octave/3.1.54/m/plot/plot.m at line 184, column 5
         line 0: undefined variable: size

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