Cylc Pygment lexer doesn't parse one-line "graph strings" correctly

[elliotfontaine]

Description

The exemple given in the docs uses a graph string spanning on multiple lines.

[scheduling]
    initial cycle point = 2000
    [[graph]]
        P1Y = """
            @wall_clock => foo? => bar
            (foo? & bar) => pub
        """

It is correctly rendered (see the previous link). But a single-line graph string without the 3 quotations marks isn't parsed correctly.

Reproducible Example

[scheduling]
    cycling mode = integer
    initial cycle point = 0
    [[graph]]
        R1/^ = foo => bar
        R1/+P1 = baz => bar

Try this in Sphinx.