Running current scons from Debian Unstable produces these warnings:
adi@chopin:~/ffado/libffado$ scons
scons: Reading SConscript files ...
scons: warning: The Options class is deprecated; use the Variables class instead.
File "/home/adi/ffado/libffado/SConstruct", line 46, in <module>
scons: warning: The BoolOption() function is deprecated; use the BoolVariable() function instead.
File "/home/adi/ffado/libffado/SConstruct", line 55, in <module>
scons: warning: The PathOption() function is deprecated; use the PathVariable() function instead.
File "/home/adi/ffado/libffado/SConstruct", line 57, in <module>
scons: warning: The EnumOption() function is deprecated; use the EnumVariable() function instead.
File "/home/adi/ffado/libffado/SConstruct", line 82, in <module>
The attached patch seems to fix the issue, but I'm not common with scons.