Reminiscent, then, of what RB described back in the 1780s, the second line giving another example of the use of "crack" in the same sense.

"On Fasten-e'en we had a rockin
Tae ca the crack and weave our stockin,
And there was muckle fun and jokin
    Ye needna doubt:
At length, we held a hearty yokin
      At sang-about".

(At that time, a "rock" or "roke" was a hand-held distaff, with "roke and reel" being the whole equipment of the distaff and the weight attached to the end of the strand of wool which was being spun as that weight was constantly rotated. By the way, in the poem "Lament for Bonny Heck, a famous Greyhound in the Kingdom of Fife", the dog in question is described as catching rabbits "by the neck/Or by the buns").