When its `try_partial` argument is `true`, `#curl_download` makes a
`HEAD` request before downloading the file using `#curl`. Currently
`try_partial` defaults to `true`, so any `#curl_download` call that
doesn't explicitly specify `try_partial: false` will make a `HEAD`
request first. This can potentially involve several requests if the
URL redirects, so it can be a bit of unnecessary overhead when a
partial download isn't needed.
Partial downloads are generally only useful when we're working with
larger files, however there's currently only one place in brew where
`#curl_download` is used and this is the case:
`CurlDownloadStrategy`. The other `#curl_download` calls are fetching
smaller [text] files and don't need to support partial downloads.
This commit changes the default `try_partial` value to `false`,
making partial downloads opt-in rather than opt-out.
We want `try_partial` to continue to default to `true` in
`CurlDownloadStrategy` and there are various ways to accomplish this.
In this commit, I've chosen to update its `#initialize` method to
accept a `try_partial` argument that defaults to `true`, as this
value can also be used in classes that inherit from
`CurlDownloadStrategy` (e.g., `HomebrewCurlDownloadStrategy`). This
instance variable is passed to `#curl_download` in related methods,
effectively maintaining the previous `try_partial: true` value, while
also allowing this value to be overridden when necessary.
Other uses of `#curl_download` in brew are
`Formulary::FromUrlLoader#load_file` and
`Cask::CaskLoader::FromURILoader#load`, which did not provide a
`try_partial` argument but should have been using
`try_partial: false`. With the `try_partial: false` default in this
commit, these calls are now fine without a `try_partial` argument.
The only other use of `#curl_download` in brew is
`SPDX#download_latest_license_data!`. These calls were previously
using `try_partial: false` but we can now omit this argument with
the new `false` default (aligning with the above).
