Executable files (svn:executable)
We convert svn:executable properties by updating the file mode directly before adding it to the Git repository.
MIME types (svn:mime-type)
GitHub internally tracks the mime-type properties of files and the commits that added them.
Ignoring unversioned items (svn:ignore)
If you've set files and directories to be ignored in Subversion, GitHub will track them internally. Files ignored by subversion clients are completely distinct from entries in a .gitignore file.
Currently unsupported properties
GitHub doesn't currently support svn:externals, svn:global-ignores, or any properties not listed above, including custom properties.