Developers may wish to see the output of the complete regression
test suite for the current version of the source repository
between releases. Current source code is available; see
-@ref{Working with source code}. Then you will need
+@ref{Working with source code}.
+
+For regression testing @code{../configure} should be run with the
+@code{--disable-optimising} option. Then you will need
to build the LilyPond binary; see @ref{Compiling LilyPond}.
Uninstalling the previous LilyPond version is not necessary, nor is