Merge repeated curl -d/--data options in Request.from_curl()

curl merges repeated -d/--data/--data-raw options into a single request
body joined with "&" (e.g. `curl -d a=1 -d b=2` sends `a=1&b=2`). scrapy's
DataAction kept only the last value, silently dropping the earlier ones, so
`Request.from_curl("curl -d a=1 -d b=2 ...")` produced a body of just `b=2`.
Accumulate the values with "&" to match curl. -H/--header and -b/--cookie
already accumulate via action="append"; -d was the only repeatable data flag
that didn't.

scrapy/utils/curl.py

@@ -23,6 +23,11 @@ class DataAction(argparse.Action):
     ) -> None:
         value = str(values)
         value = value.removeprefix("$")
+        # curl merges repeated -d/--data/--data-raw options into a single body
+        # joined with "&"; mirror that instead of keeping only the last one.
+        previous = getattr(namespace, self.dest, None)
+        if previous is not None:
+            value = f"{previous}&{value}"
         setattr(namespace, self.dest, value)
 
 

tests/test_utils_curl.py

@@ -163,6 +163,39 @@ class TestCurlToRequestKwargs:
         }
         self._test_command(curl_command, expected_result)
 
+    def test_post_data_multiple(self):
+        # curl merges repeated -d/--data/--data-raw options into a single body
+        # joined with "&"; scrapy must do the same, not keep only the last one.
+        curl_command = "curl 'https://www.example.org/' -d 'a=1' -d 'b=2' -d 'c=3'"
+        expected_result = {
+            "method": "POST",
+            "url": "https://www.example.org/",
+            "body": "a=1&b=2&c=3",
+        }
+        self._test_command(curl_command, expected_result)
+
+    def test_post_data_multiple_mixed_flag_names(self):
+        curl_command = (
+            "curl 'https://www.example.org/' --data 'a=1' --data-raw 'b=2' -d 'c=3'"
+        )
+        expected_result = {
+            "method": "POST",
+            "url": "https://www.example.org/",
+            "body": "a=1&b=2&c=3",
+        }
+        self._test_command(curl_command, expected_result)
+
+    def test_post_data_multiple_with_string_prefix(self):
+        # The leading "$" left by bash $'...' quoting is stripped per option,
+        # before the values are merged.
+        curl_command = "curl 'https://www.example.org/' -d $'a=1' -d $'b=2'"
+        expected_result = {
+            "method": "POST",
+            "url": "https://www.example.org/",
+            "body": "a=1&b=2",
+        }
+        self._test_command(curl_command, expected_result)
+
     def test_explicit_get_with_data(self):
         curl_command = "curl httpbin.org/anything -X GET --data asdf"
         expected_result = {