.curlrc has conflict with homebrew

with .curlrc, I can't upgrade freetype via brew

```
brew upgrade freetype
```

it gives such error:

```
$ brew upgrade
==> Upgrading 7 outdated packages, with result:
fontconfig 2.11.1_2, gd 2.1.1_2, go 1.6, imagemagick 6.9.3-6, speedtest_cli 0.3.4, webp 0.5.0, wine 1.8.1
==> Upgrading fontconfig
==> Installing dependencies for fontconfig: freetype
==> Installing fontconfig dependency: freetype
==> Downloading https://downloads.sf.net/project/freetype/freetype2/2.6.3/freetype-2.6.3.tar.bz2
==> Downloading from http://sourceforge.net/projects/freetype/files/freetype2/2.6.3/freetype-2.6.3.tar.bz2/download?use_mirror=tenet
######################################################################## 100.0%
Error: SHA256 mismatch
Expected: 371e707aa522acf5b15ce93f11183c725b8ed1ee8546d7b3af549863045863a2
Actual: 5caaf8b62aa5bb59c2511df6926eae41e7ab98cc2e751a27db76291634797e66
Archive: /Library/Caches/Homebrew/freetype-2.6.3.tar.bz2
To retry an incomplete download, remove the file above.
```

Start by reading .curlrc and reproducing the brew upgrade freetype command shown in the report. Compare the download and checksum behavior with the configuration enabled and disabled; done means the upgrade no longer produces the reported SHA256 mismatch.

Written by the indexing model from the issue text.