gistfile1.swift

import UIKit

class CommentCountCell: UITableViewCell {
    lazy var child: UIView = {
        var child = UIView(frame: CGRect.zero)
        child.translatesAutoresizingMaskIntoConstraints = false
        child.backgroundColor = .red
        return child
    }()

    override init(style: UITableViewCellStyle, reuseIdentifier: String?) {
        super.init(style: style, reuseIdentifier: reuseIdentifier)
        contentView.addSubview(child)
    }

    required init?(coder: NSCoder) {
        super.init(coder: coder)
    }
    
    var shouldSetupConstraints = true
    override func updateConstraints() {
        if shouldSetupConstraints {
            child.topAnchor.constraint(equalTo: contentView.topAnchor).isActive = true
            child.leftAnchor.constraint(equalTo: contentView.leftAnchor).isActive = true
            child.rightAnchor.constraint(equalTo: contentView.rightAnchor).isActive = true
            child.bottomAnchor.constraint(equalTo: contentView.bottomAnchor).isActive = true
            child.heightAnchor.constraint(equalToConstant: 100).isActive = true
            shouldSetupConstraints = false
        }
        super.updateConstraints()
    }
}

Probably at least one of the constraints in the following list is one you don't want. 
Try this: 
(1) look at each constraint and try to figure out which you don't expect; 
(2) find the code that added the unwanted constraint or constraints and fix it. 
(
    "<NSLayoutConstraint:0x1c4285fa0 V:|-(0)-[UIView:0x11be2bdc0]   (active, names: '|':UITableViewCellContentView:0x11be2b2d0 )>",
    "<NSLayoutConstraint:0x1c4286180 UIView:0x11be2bdc0.bottom == UITableViewCellContentView:0x11be2b2d0.bottom   (active)>",
    "<NSLayoutConstraint:0x1c42861d0 UIView:0x11be2bdc0.height == 100   (active)>",
    "<NSLayoutConstraint:0x1c4285d70 'UIView-Encapsulated-Layout-Height' UITableViewCellContentView:0x11be2b2d0.height == 99999   (active)>"
)```