No rule to make target `tbcover.m', needed by `all-am'

[Julien Bect]

Dear maintainers,

After updating to the latest revision on default, I get the following 
when doing "make" :

make[2]: *** No rule to make target `tbcover.m', needed by `all-am'.  Stop.
make[1]: *** [all-recursive] Error 1
make: *** [all] Error 2

Am I doing something wrong ? Or perhaps is there really a missing rule 
somewhere ?

Best regards,

Julien.