Adapt to upstream FileResponse logic

The ``send_header_only`` attribute has been removed in starlette
(encode/starlette#2366), and replaced with
`scope["method"].upper() == "HEAD"`

lib/galaxy/webapps/base/api.py

@@ -77,15 +77,11 @@ def __init__(
             path, status_code, headers, media_type, background, filename, stat_result, method, content_disposition_type
         )
         self.headers["accept-ranges"] = "bytes"
-        send_header_only = self.nginx_x_accel_redirect_base or self.apache_xsendfile
+        self.send_header_only = self.nginx_x_accel_redirect_base or self.apache_xsendfile
         if self.nginx_x_accel_redirect_base:
             self.headers["x-accel-redirect"] = self.nginx_x_accel_redirect_base + os.path.abspath(path)
         elif self.apache_xsendfile:
             self.headers["x-sendfile"] = os.path.abspath(path)
-        if not self.send_header_only and send_header_only:
-            # Not a head request, but nginx_x_accel_redirect_base / send_header_only, we don't send a body
-            self.send_header_only = True
-            self.headers["content-length"] = "0"
 
     async def __call__(self, scope: "Scope", receive: "Receive", send: "Send") -> None:
         if self.stat_result is None:
@@ -100,9 +96,14 @@ async def __call__(self, scope: "Scope", receive: "Receive", send: "Send") -> No
                     raise RuntimeError(f"File at path {self.path} is not a file.")
 
         # This is where we diverge from the superclass, this adds support for byte range requests
+        if not scope["method"].upper() == "HEAD" and self.send_header_only:
+            # Not a head request, but nginx_x_accel_redirect_base / send_header_only, we don't send a body
+            self.send_header_only = True
+            self.headers["content-length"] = "0"
+
         start = 0
         end = stat_result.st_size - 1
-        if not self.send_header_only:
+        if not scope["method"].upper() == "HEAD":
             http_range = ""
             for key, value in scope["headers"]:
                 if key == b"range":