^^^^
For anyone else reading this when replacing any brake hoses , pipes , calipers or whatever .
Accepted practice is to press down and jam the brake pedal on so that the master cylinder seals go beyond the feed from the reservoir therefore no more fluid , or air for that matter can enter the system . Might need to open a bleed valve to get the brake pedal down far enough .
This will prevent the reservoir draining whilst replacing any parts . It might still drip slightly for a while but prevents everything draining out . Might still need to do the abs bleed if enough fluid has drained from whatever circuit you were working on .
Sometimes the abs bleed is the the only way if air got into the abs block .