Why empty in LD_LIBRARY_PATH be interpreted as `use the current directory`?

[Paul Smith]

On Wed, 2019-05-08 at 15:20 +0800, ronyweng wrote:
> LD_LIBRARY_PATH="${GVM_OVERLAY_PREFIX}/lib:${LD_LIBRARY_PATH}"

This should be written as:

  LD_LIBRARY_PATH="${GVM_OVERLAY_PREFIX}/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"