Before the change of law procedures of Law 42.18 Players’ conduct would be followed in this situation.
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This case is now covered by the new code of laws NEW CODE OF LAWS - OCTOBER 2017, thanks to @gout for looking into this and reminding me in comment.
Law 25.7 Restriction on the striker’s runner states:
25.7.1 Once the ball comes into play, the runner for an injured batsman who is the striker
shall have part of his/her person or bat grounded behind the popping crease until the
ball reaches the striker or passes the popping crease, whichever is the sooner.
25.7.2 If the striker’s end umpire considers the runner for an injured striker to be in breach
of this restriction then, if the ball does not become dead for any other reason, he shall
call and signal Dead ball as soon as the ball reaches the boundary or at the
completion of the first run. However, he/she shall delay the call of Dead ball to allow
the opportunity for a catch to be completed.
This law will now restrict the movement of runner for injured striker before he strikes the ball.
This new set of laws with few other that have been changed will take effect around the world from 1 October 2017.