[mod_webdav] detect truncated copy_file_range()
[mod_webdav] detect truncated copy_file_range()

detect truncated file when using copy_file_range(), even though
this should not happen with lighttpd-created temporary files

lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,gstrauss/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,lighttpd/lighttpd1.4,gstrauss/lighttpd1.4