Looks like it may have been from this post:
Also, look at the "sep=" option on this help page:
gpsoft.com.au/help/opus12/i ... enames.htm
But, I think things are complicated by the fact that the command you're using has both sourcepath and file specified separately. (Not sure why they're separate.) To fix that issue, look at the {allfilepath} argument on the same Help page.
If I understand correctly, this:
"C:\Program Files\TortoiseSVN\bin\TortoiseProc.exe" /command:commit /path:"{sourcepath$}{file}" /closeonend:3
would become this:
"C:\Program Files\TortoiseSVN\bin\TortoiseProc.exe" /command:commit /path:"{allfilepath|sep=*}" /closeonend:3