apply import merging for fbcode (8 of 11)

Summary:
Applies new import merging and sorting from µsort v1.0.

When merging imports, µsort will make a best-effort to move associated
comments to match merged elements, but there are known limitations due to
the diynamic nature of Python and developer tooling. These changes should
not produce any dangerous runtime changes, but may require touch-ups to
satisfy linters and other tooling.

Note that µsort uses case-insensitive, lexicographical sorting, which
results in a different ordering compared to isort. This provides a more
consistent sorting order, matching the case-insensitive order used when
sorting import statements by module name, and ensures that "frog", "FROG",
and "Frog" always sort next to each other.

For details on µsort's sorting and merging semantics, see the user guide:
https://usort.readthedocs.io/en/stable/guide.html#sorting

Reviewed By: lisroach

Differential Revision: D36402214

fbshipit-source-id: b641bfa9d46242188524d4ae2c44998922a62b4c

build/fbcode_builder/getdeps.py

@@ -21,15 +21,15 @@ from getdeps.buildopts import setup_build_options
 from getdeps.dyndeps import create_dyn_dep_munger
 from getdeps.errors import TransientFailure
 from getdeps.fetcher import (
-    SystemPackageFetcher,
     file_name_is_cmake_file,
     list_files_under_dir_newer_than_timestamp,
+    SystemPackageFetcher,
 )
 from getdeps.load import ManifestLoader
 from getdeps.manifest import ManifestParser
 from getdeps.platform import HostType
 from getdeps.runcmd import run_cmd
-from getdeps.subcmd import SubCmd, add_subcommands, cmd
+from getdeps.subcmd import add_subcommands, cmd, SubCmd
 
 
 try: