git log - how to find out latest stable/14 breakage

Hello,

suddenly, there are
lib/libifconfig/libifconfig_sfp_tables.tpl.c
  create mode 100644 lib/libifconfig/libifconfig_sfp_tables.tpl.h
  create mode 100644 lib/libifconfig/libifconfig_sfp_tables_internal.tpl.h

while lib/libifconfig/libifconfig_sfp.h
still reads
#include <libifconfig_sfp_tables.h>

(note (new) the .tpl.h suffix).

Neither on CLI with 'git log' nor via cgit I can figure out when/what 
commit changed that filenames.

How can you all manage your daily jobs with git?!?!  For me as a 
part-time RCS user, git is a huge regression.  Never had anything to 
lookup/read twice with subversion or cvs in the past, but never found 
out how I'm supposed to use git.  I'm looking up usage again and again 
and again... is it I'm getting old probably :-(

Thanks for hints,

-harry