FIX: if first argument in BaseExcelReader.__init__ is bytes, create a buffer

Author: mwtoews

pandas/io/excel/_base.py

@@ -404,6 +404,9 @@ def read_excel(
 
 class BaseExcelReader(metaclass=abc.ABCMeta):
     def __init__(self, filepath_or_buffer, storage_options: StorageOptions = None):
+        # first argument can also be bytes, so create a buffer
+        if isinstance(filepath_or_buffer, bytes):
+            filepath_or_buffer = BytesIO(filepath_or_buffer)
         self.handles = IOHandles(
             handle=filepath_or_buffer, compression={"method": None}
         )
@@ -422,8 +425,6 @@ def __init__(self, filepath_or_buffer, storage_options: StorageOptions = None):
             except Exception:
                 self.close()
                 raise
-        elif isinstance(self.handles.handle, bytes):
-            self.book = self.load_workbook(BytesIO(self.handles.handle))
         else:
             raise ValueError(
                 "Must explicitly set engine if not passing in buffer or path for io."