Every time you check out a script file from Subversion on a Unix system, the file is missing the execute permission and you have to manually perform a chmod +x every time. This usually happens if the file was either originally added without the permission set or if it was added to Subversion from a Windows system. But more to the point, it is extremely annoying.
The solution to this involves adding an internal Subversion property called svn:executable to the script file(s) in question. The property can either be set using Tortoise SVN from a Windows system (as described by a posting on Late Night PC found by my colleague MÃ¡tÃ© RÃ¡cz) or can be done from the command-line as follows:
$ svn propset svn:executable true myscript.sh
Both methods work and required a SVN commit afterwards.