dCache with file upload in progress doesn't provide MLST Size

During file upload gfal-stat with gsiftp:// protocol for dCache reports size 2**64-1, while same request with davs, https, root return returns filesize 0 (other SE return 0 or size of partially uploaded for all protocols). dCache doesn't return "Size=number;" for gsiftp MLST request during file upload. FTS database filesize column can't deal with such big number, exception is thrown and FTS gets effectively stuck.

Gfal stat should return filesize 0 not -1 (2**64-1) when there is no Size information returned for MLST gsiftp reuqest.