Attempt to handle requests for items in the middle of upload

It seems possible that this is a source of trouble in #2.  So we'll
keep a record of all documents being uploaded right now, and check
that if we don't find a document in the cloud or in the buffers.
This could go sideways very quickly if we try to do something with
this document.  But hopefully in practice it will only be setting
attributes or something similarly innocuous.

rmfuse/fuse.py

@@ -120,6 +120,7 @@ def __init__(self, mode):
         self.mode_file = ModeFile(self)
         self.inode_map[self.next_inode()] = self.mode_file.id
         self.buffers = dict()
+        self.uploading = dict()
         self._prev_read_fail_count = 0
 
     def next_inode(self):
@@ -145,6 +146,12 @@ async def get_by_id(self, id_):
             for item, _ in self.buffers.values():
                 if item.id == id_:
                     return item
+            # Or it may be uploading right now.  This may lead to tears.
+            for item in self.uploading.values():
+                if item.id == id_:
+                    logging.warning(f'Getting Item {id_} during upload.  '
+                                    'This may lead to odd behavior!')
+                    return item
             logging.error(f'Attempt to get non-existent Item {id_}')
             raise fuse.FUSEError(errno.ENOENT)
 
@@ -368,11 +375,15 @@ async def release(self, fh):
         else:
             log.error(f'Error: Not a PDF or EPUB file (file was {document.name})')
             raise fuse.FUSEError(errno.EIO)  # Unfortunately, this will be ignored
+
+        self.uploading[fh] = document
         try:
             await document.upload(io.BytesIO(data), type_)
         except ApiError as error:
             log.error(f'API Error: {error}')
             raise fuse.FUSEError(errno.EREMOTEIO)  # Unfortunately, this will be ignored
+        finally:
+            del self.uploading[fh]
 
     @async_op
     async def rename(self, p_inode_old, name_old, p_inode_new, name_new, flags, ctx=None):