Dont import any pywin32 modules during startup

Also dont import fcntl

src/calibre/__init__.py

@@ -18,17 +18,15 @@ except EnvironmentError:
 
 from calibre.constants import (iswindows, ismacos, islinux, isfrozen,
         isbsd, preferred_encoding, __appname__, __version__, __author__,
-        win32event, win32api, winerror, fcntl, plugins,
+        fcntl, plugins, filesystem_encoding, config_dir)
-        filesystem_encoding, config_dir)
+from calibre.startup import winutil
-from calibre.startup import winutil, winutilerror
 from calibre.utils.icu import safe_chr
 from calibre.prints import prints
 
 if False:
     # Prevent pyflakes from complaining
-    winutil, winutilerror, __appname__, islinux, __version__
+    winutil, __appname__, islinux, __version__
-    fcntl, win32event, isfrozen, __author__
+    fcntl, isfrozen, __author__, isbsd, config_dir, plugins
-    winerror, win32api, isbsd, config_dir, plugins
 
 _mt_inited = False
 

src/calibre/constants.py

@@ -2,7 +2,7 @@
 # vim:fileencoding=utf-8
 # License: GPLv3 Copyright: 2015, Kovid Goyal <kovid at kovidgoyal.net>
 from polyglot.builtins import map, unicode_type, environ_item, hasenv, getenv
-import sys, locale, codecs, os, importlib, collections
+import sys, locale, codecs, os, collections
 
 __appname__   = 'calibre'
 numeric_version = (5, 3, 0)
@@ -50,10 +50,6 @@ try:
 except:
     preferred_encoding = 'utf-8'
 
-win32event = importlib.import_module('win32event') if iswindows else None
-winerror   = importlib.import_module('winerror') if iswindows else None
-win32api   = importlib.import_module('win32api') if iswindows else None
-fcntl      = None if iswindows else importlib.import_module('fcntl')
 dark_link_color = '#6cb4ee'
 builtin_colors_light = {
     'yellow': '#ffeb6b',

src/calibre/utils/lock.py

@@ -11,7 +11,7 @@ import time
 from functools import partial
 
 from calibre.constants import (
-    __appname__, fcntl, filesystem_encoding, islinux, ismacos, iswindows
+    __appname__, filesystem_encoding, islinux, ismacos, iswindows
 )
 from calibre_extensions import speedup
 from calibre.utils.monotonic import monotonic
@@ -23,6 +23,7 @@ if iswindows:
     excl_file_mode = stat.S_IREAD | stat.S_IWRITE
 else:
     excl_file_mode = stat.S_IRUSR | stat.S_IWUSR | stat.S_IRGRP | stat.S_IROTH
+    import fcntl
 
 
 def unix_open(path):

src/calibre/utils/test_lock.py

@@ -12,7 +12,7 @@ import time
 import unittest
 from threading import Thread
 
-from calibre.constants import cache_dir, fcntl, iswindows
+from calibre.constants import cache_dir, iswindows
 from calibre.utils.lock import ExclusiveFile, create_single_instance_mutex, unix_open
 from calibre.utils.tdir_in_cache import (
     clean_tdirs_in, is_tdir_locked, retry_lock_tdir, tdir_in_cache, tdirs_in,
@@ -84,6 +84,7 @@ class IPCLockTest(unittest.TestCase):
             t.start(), t.join()
             self.assertIs(t.locked, False)
         if not iswindows:
+            import fcntl
             with unix_open(fname) as f:
                 self.assertEqual(
                     1, fcntl.fcntl(f.fileno(), fcntl.F_GETFD) & fcntl.FD_CLOEXEC