This is modeled after the upstream commit which removes ureq as a dependency.

diff --git a/Cargo.toml b/Cargo.toml
index 5a787e1..27171c7 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -201,26 +201,3 @@ test-external-apis = []
 upgrade = ["cli"]
 vendored-libgit2 = ["git2/vendored-libgit2"]
 vendored-openssl = ["git2/vendored-openssl"]
-
-[target."cfg(any(target_arch = \"x86_64\", target_arch = \"arm\", target_arch = \"x86\", target_arch = \"aarch64\"))".dependencies.ureq]
-version = "2.7.1"
-features = [
-    "tls",
-    "json",
-    "socks",
-    "socks-proxy",
-]
-default-features = false
-
-[target."cfg(not(any(target_arch = \"x86_64\", target_arch = \"arm\", target_arch = \"x86\", target_arch = \"aarch64\")))".dependencies.native-tls]
-version = "^0.2"
-
-[target."cfg(not(any(target_arch = \"x86_64\", target_arch = \"arm\", target_arch = \"x86\", target_arch = \"aarch64\")))".dependencies.ureq]
-version = "2.7.1"
-features = [
-    "native-tls",
-    "json",
-    "socks",
-    "socks-proxy",
-]
-default-features = false
guix/about/'>about</a><a href='/guix/'>summary</a><a href='/guix/refs/?id=da4006d474280f0f20449176c20b148855359194'>refs</a><a class='active' href='/guix/log/gnu/installer/substitutes.scm'>log</a><a href='/guix/tree/gnu/installer/substitutes.scm?id=da4006d474280f0f20449176c20b148855359194'>tree</a><a href='/guix/commit/gnu/installer/substitutes.scm?id=da4006d474280f0f20449176c20b148855359194'>commit</a><a href='/guix/diff/gnu/installer/substitutes.scm?id=da4006d474280f0f20449176c20b148855359194'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/gnu/installer/substitutes.scm'>
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<div class='path'>path: <a href='/guix/log/?id=da4006d474280f0f20449176c20b148855359194'>root</a>/<a href='/guix/log/gnu?id=da4006d474280f0f20449176c20b148855359194'>gnu</a>/<a href='/guix/log/gnu/installer?id=da4006d474280f0f20449176c20b148855359194'>installer</a>/<a href='/guix/log/gnu/installer/substitutes.scm?id=da4006d474280f0f20449176c20b148855359194'>substitutes.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/installer/substitutes.scm?id=da4006d474280f0f20449176c20b148855359194&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/substitutes.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>