Merge branch 'staging-next' into staging

doc/languages-frameworks/rust.section.md

@@ -119,6 +119,18 @@ The above are just guidelines, and exceptions may be granted on a case-by-case b
 However, please check if it's possible to disable a problematic subset of the
 test suite and leave a comment explaining your reasoning.
 
+#### Setting `test-threads`
+
+`buildRustPackage` will use parallel test threads by default,
+sometimes it may be necessary to disable this so the tests run consecutively.
+
+```nix
+rustPlatform.buildRustPackage {
+  /* ... */
+  cargoParallelTestThreads = false;
+}
+```
+
 ### Building a package in `debug` mode
 
 By default, `buildRustPackage` will use `release` mode for builds. If a package

doc/stdenv/stdenv.xml

@@ -1636,10 +1636,6 @@ substitute ./foo.in ./foo.out \
     --subst-var someVar
 </programlisting>
      </para>
-     <para>
-      <function>substitute</function> is implemented using the <command
-      xlink:href="http://replace.richardlloyd.org.uk/">replace</command> command. Unlike with the <command>sed</command> command, you don’t have to worry about escaping special characters. It supports performing substitutions on binary files (such as executables), though there you’ll probably want to make sure that the replacement string is as long as the replaced string.
-     </para>
     </listitem>
    </varlistentry>
    <varlistentry xml:id='fun-substituteInPlace'>