The binary is installed as a detached "debug symbols" ELF file, but it does not appear to have debug information associated with it.
A common cause is not passing -g to GCC when compiling.
Implementation detail: Lintian checks for the ".debug_line" and the ".debug_str" sections. If either of these are present, the binary is assumed to contain debug information.
Refer to https://bugs.debian.org/668437 for details.