vagrant: 2.2.14 -> 2.2.15

ChangeLog: https://github.com/hashicorp/vagrant/blob/v2.2.15/CHANGELOG.md#2215-march-30-2021

Also had to revert a change which improved plugin-errors a bit since it
changed the dependency resolution in a way that broke `vagrant-libvirt`
from `$out/vagrant-plugins/plugins.d`.

pkgs/development/tools/vagrant/default.nix

@@ -5,9 +5,9 @@
 let
   # NOTE: bumping the version and updating the hash is insufficient;
   # you must use bundix to generate a new gemset.nix in the Vagrant source.
-  version = "2.2.14";
+  version = "2.2.15";
   url = "https://github.com/hashicorp/vagrant/archive/v${version}.tar.gz";
-  sha256 = "sha256-vsb7RFjT9l4N6BzwIvVLcRtA4n/c8jk20B6RUMkyhJs=";
+  sha256 = "sha256-mMnHJtXLfkZ5O0UF89kHsqBnPg9uQ5l8IYoL5TMMyD8=";
 
   deps = bundlerEnv rec {
     name = "${pname}-${version}";
@@ -54,6 +54,7 @@ in buildRubyGem rec {
     ./unofficial-installation-nowarn.patch
     ./use-system-bundler-version.patch
     ./0004-Support-system-installed-plugins.patch
+    ./0001-Revert-Merge-pull-request-12225-from-chrisroberts-re.patch
   ];
 
   postPatch = ''