[fast-deps] Late download logs are over indented

[McSinyx]

Environment

• pip version: 20.2.1 current master
• Python version: irrelevant
• OS: irrelevant

Description

During final preparation that downloads the wheels skipped wheels, the logs are over-indented which make the overall output a bit confusing:

$ pip --use-feature=2020-resolver --use-feature=fast-deps download scipy
WARNING: pip is using lazily downloaded wheels using HTTP range requests to obtain dependency information. This experimental feature is enabled through --use-feature=fast-deps and it is not ready for production.
Collecting scipy
  Obtaining dependency information from scipy 1.5.2
Collecting numpy>=1.14.5
  Obtaining dependency information from numpy 1.19.1
  Downloading scipy-1.5.2-cp38-cp38-manylinux1_x86_64.whl (25.7 MB)
     |████████████████████████████████| 25.7 MB 7.8 MB/s 
  Saved ./scipy-1.5.2-cp38-cp38-manylinux1_x86_64.whl
  Downloading numpy-1.19.1-cp38-cp38-manylinux2010_x86_64.whl (14.5 MB)
     |████████████████████████████████| 14.5 MB 7.2 MB/s 
  Saved ./numpy-1.19.1-cp38-cp38-manylinux2010_x86_64.whl

This is due to _prepare_linked_requirement assumes the indentation level, which is not needed when called from prepare_linked_requirement_more:

pip/src/pip/_internal/operations/prepare.py

Lines 491 to 510 in 709ad37

	return self._prepare_linked_requirement(req, parallel_builds)
	def prepare_linked_requirement_more(self, req, parallel_builds=False):
	# type: (InstallRequirement, bool) -> None
	"""Prepare a linked requirement more, if needed."""
	if not req.needs_more_preparation:
	return
	self._prepare_linked_requirement(req, parallel_builds)
	def _prepare_linked_requirement(self, req, parallel_builds):
	# type: (InstallRequirement, bool) -> Distribution
	assert req.link
	link = req.link
	if link.is_wheel and self.wheel_download_dir:
	# Download wheels to a dedicated dir when doing `pip wheel`.
	download_dir = self.wheel_download_dir
	else:
	download_dir = self.download_dir
	with indent_log():

Expected behavior

$ pip --use-feature=2020-resolver --use-feature=fast-deps download scipy
WARNING: pip is using lazily downloaded wheels using HTTP range requests to obtain dependency information. This experimental feature is enabled through --use-feature=fast-deps and it is not ready for production.
Collecting scipy
  Obtaining dependency information from scipy 1.5.2
Collecting numpy>=1.14.5
  Obtaining dependency information from numpy 1.19.1
Downloading scipy-1.5.2-cp38-cp38-manylinux1_x86_64.whl (25.7 MB)
  |████████████████████████████████| 25.7 MB 7.8 MB/s 
Saved ./scipy-1.5.2-cp38-cp38-manylinux1_x86_64.whl
Downloading numpy-1.19.1-cp38-cp38-manylinux2010_x86_64.whl (14.5 MB)
   |████████████████████████████████| 14.5 MB 7.2 MB/s 
Saved ./numpy-1.19.1-cp38-cp38-manylinux2010_x86_64.whl