proper way to override the download command?

doc/todo/easy_way_to_reproduce_normal_download_command.mdwn

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+so there's a `annex.web-download-command` settings, great! i have used
+it to do bandwidth limitations with:
+
+    wget --limit-rate=$download -O %file %url
+
+...and it works well.. however, i notice the output is different, and
+that's because once we override that setting, git-annex doesn't add
+other magic settings it uses. so by turning that thing on and off and
+inspecting the process list, i was able to figure out that the command
+is actually:
+
+    wget -q --show-progress --clobber -c --limit-rate=$download -O %file %url
+
+that gets me closer to the command generated by git-annex. however, i
+am not sure the `--clobber` and `-c` flags should always be
+present. furthermore, the `--user-agent
+git-annex/5.20150610+gitg608172f-1~ndall+1` flag is missing.
+
+could there be an (optional) %useragent interpolation to fix that?
+
+what about the other settings, is it okay to hardcode those?
+
+maybe this would be easier if there would be an options override just
+like rsync, but separate ones for curl and wget... --[[anarcat]]