Do not unintentionally load TIFF format at first

[radarhere]

from PIL import Image
Image.preinit()
print(Image.ID)

prints

['BMP', 'DIB', 'GIF', 'TIFF', 'JPEG', 'PPM', 'PNG']

But preinit() doesn't list TIFF. In fact, it is commented out

Pillow/src/PIL/Image.py

Lines 321 to 364 in 43bb035

	def preinit():
	"""Explicitly load standard file format drivers."""
	global _initialized
	if _initialized >= 1:
	return
	try:
	from . import BmpImagePlugin
	assert BmpImagePlugin
	except ImportError:
	pass
	try:
	from . import GifImagePlugin
	assert GifImagePlugin
	except ImportError:
	pass
	try:
	from . import JpegImagePlugin
	assert JpegImagePlugin
	except ImportError:
	pass
	try:
	from . import PpmImagePlugin
	assert PpmImagePlugin
	except ImportError:
	pass
	try:
	from . import PngImagePlugin
	assert PngImagePlugin
	except ImportError:
	pass
	# try:
	# import TiffImagePlugin
	# assert TiffImagePlugin
	# except ImportError:
	# pass
	_initialized = 1

So why is TIFF part of the preinit list? Because when JPEG is loaded, it imports TiffImagePlugin.

Pillow/src/PIL/JpegImagePlugin.py

Line 44 in 43bb035

from . import Image, ImageFile, TiffImagePlugin

This PR changes the import to only run when it is used, removing TIFF from the list.