[Blob][Fileshare] Ensured that download fails if blob/file modified m…

…id download (Azure#19276)

* Ensured that download fails if blob/file modified mid download

* fixed linter

* ResourceModifiedError

sdk/storage/azure-storage-blob/azure/storage/blob/_download.py

@@ -460,10 +460,8 @@ def _initial_request(self):
         # If the file is small, the download is complete at this point.
         # If file size is large, download the rest of the file in chunks.
         if response.properties.size != self.size:
-            # Lock on the etag. This can be overriden by the user by specifying '*'
             if self._request_options.get("modified_access_conditions"):
-                if not self._request_options["modified_access_conditions"].if_match:
-                    self._request_options["modified_access_conditions"].if_match = response.properties.etag
+                self._request_options["modified_access_conditions"].if_match = response.properties.etag
         else:
             self._download_complete = True
         return response

sdk/storage/azure-storage-blob/azure/storage/blob/aio/_download_async.py

@@ -352,10 +352,8 @@ async def _initial_request(self):
         # If the file is small, the download is complete at this point.
         # If file size is large, download the rest of the file in chunks.
         if response.properties.size != self.size:
-            # Lock on the etag. This can be overriden by the user by specifying '*'
             if self._request_options.get('modified_access_conditions'):
-                if not self._request_options['modified_access_conditions'].if_match:
-                    self._request_options['modified_access_conditions'].if_match = response.properties.etag
+                self._request_options['modified_access_conditions'].if_match = response.properties.etag
         else:
             self._download_complete = True
         return response