eol: ignore IOError from deleted files in commitctx
A Mercurial repo signals a file is deleted by raising IOError when the
file's data is requested. This IOError is normally caught by
localrepository.commitctx. With the eol extension enabled and EOL
mappings in place, the eolrepo subclass should ignore IOError because
a deleted file has no line endings to process.
This issue exhibited itself when performing an incremental hg convert
of a revision with deleted files to a repo with an existing .hgeol
file.