Bugs on the textures of the Nether Wart

Issues about the textures of different stages of the growing nether wart.
We all know that there's 4 growing stages for the nether wart. However since the version of 0.15.0, the 2nd and the 3rd stage use the original 3rd and 4th stages' textures respectively, while the 4th stage or the final grown stage uses the 1st stages' textures. This is quite confusing for players. For more details, please watch the attachment.