The SVN keywords for files in the build tree (at least on the files in hardware/arduino/cores/arduino) are not working properly.
Many files have old stale SVN keywords in them.
many are 3+ years old... :o
The files don't seem to have the proper the keywords property
value to enable keyword exapansion.
This file was modified just days ago and is at revision 977 yet the SVN Id keyword in the source code is from 3 years ago at revision 248
because keyword expansion is not properly enabled.
SVN is not like SCCS/RCS/CVS that have keyword expansion
permanently enabled.
Having out of date revision information is worse than having no revision information at all.
The SVN properties need to be updated to allow the SVN keywords to be expanded properly.
There are simple commands to enable keyword expansion
it only has to be done once.
Then the keyword expansion works again, and you can forget about it.
This can only be corrected by one of the arduino project owners.
I'll go open an issue on the issues list so this doesn't get lost.