Decrease imports reach on wheel build.

Moving _is_debugpy_available to .debugger to avoid having import that
much of the package on wheel building. In particular this was forcing
`psutil`  to be importable to build this package

Author: Carreau

ipykernel/debugger.py

@@ -19,10 +19,14 @@
 
 from .compiler import (get_file_name, get_tmp_directory, get_tmp_hash_seed)
 
-# This import is required to have the next ones working...
-from debugpy.server import api  # noqa
-from _pydevd_bundle import pydevd_frame_utils
-from _pydevd_bundle.pydevd_suspended_frames import SuspendedFramesManager, _FramesTracker
+try:
+    # This import is required to have the next ones working...
+    from debugpy.server import api  # noqa
+    from _pydevd_bundle import pydevd_frame_utils
+    from _pydevd_bundle.pydevd_suspended_frames import SuspendedFramesManager, _FramesTracker
+    _is_debugpy_available = True
+except ImportError:
+    _is_debugpy_available = False
 
 # Required for backwards compatiblity
 ROUTING_ID = getattr(zmq, 'ROUTING_ID', None) or zmq.IDENTITY

ipykernel/ipkernel.py

@@ -18,6 +18,7 @@
 from .zmqshell import ZMQInteractiveShell
 from .eventloops import _use_appnope
 from .compiler import XCachingCompiler
+from .debugger import Debugger, _is_debugpy_available
 
 try:
     from IPython.core.interactiveshell import _asyncio_runner
@@ -33,12 +34,6 @@
 except ImportError:
     _use_experimental_60_completion = False
 
-try:
-    import debugpy
-    from .debugger import Debugger
-    _is_debugpy_available = True
-except ImportError:
-    _is_debugpy_available = False
 
 _EXPERIMENTAL_KEY_NAME = '_jupyter_types_experimental'
 

ipykernel/kernelspec.py

@@ -13,7 +13,7 @@
 
 from jupyter_client.kernelspec import KernelSpecManager
 
-from .ipkernel import _is_debugpy_available
+from .debugger import _is_debugpy_available
 
 pjoin = os.path.join