Today decided to upgrade FS, after almost 5 months from last upgrade, and executed 'make current'

However, it failed with the following errors:

...
 create mode 100644 src/mod/event_handlers/mod_cdr_mongodb/mod_cdr_mongodb.c
 delete mode 100644 src/mod/timers/.empty
 create mode 100644 swig_common.i
make[1]: Leaving directory `/usr/local/src/freeswitch'
make all
make[1]: Entering directory `/usr/local/src/freeswitch'
cd . && /bin/sh /usr/local/src/freeswitch/build/config/missing --run aclocal-1.9
 cd . && /bin/sh /usr/local/src/freeswitch/build/config/missing --run automake-1.9 --gnu
configure.in:27: required file `build/config/config.sub' not found
make[1]: *** [Makefile.in] Error 1
make[1]: Leaving directory `/usr/local/src/freeswitch'
make: *** [current] Error 2


Could you please hint what has changed since then or what I am doing wrong?

Thank you,
Vitalie