Weapon XP bar in weapon customization screen is inaccurate

The weapon XP bar shown in weapon selection/customization does not accurately show the percentage of XP to the next weapon level.

The weapon XP bar shown in the post-match progression screen is accurate. I have verified this by observing that when the post-match progression weapon XP bar was very close to full, I would level up that weapon in the next match in 1-2 kills. Yet when I look at the weapon XP bar in weapon customization in that situation, it is a little over 50% full.

This bug has been in the game since at least the open beta.