Inconsistent line ending style
On the TortoiseSVN forums someone suggested that this might have occurred because someone edited the file in multiple editors, and somewhere in the process happened to slip in a line feed particular to their editor which version 1.7.4 of our Apache Subversion server found disagreeable.
To work around this, I was able to open the file in Microsoft Word, then save the file as plain text, with Windows (Default) chosen for text encoding:
Why SVN server scrutinizes the line feeds is unclear to me, but thankfully whomever committed the offending change made it to just this one file out of hundreds in the repository.
