Ruby 2.6.3 brew tests fixes

Library/Homebrew/system_command.rb

@@ -96,7 +96,7 @@ class SystemCommand
 
     return [] if set_variables.empty?
 
-    ["env", *set_variables]
+    ["/usr/bin/env", *set_variables]
   end
 
   def sudo_prefix

Library/Homebrew/test/support/fixtures/bottles/testball_bottle-0.1.catalina.bottle.tar.gz

@@ -0,0 +1 @@
+testball_bottle-0.1.yosemite.bottle.tar.gz

Library/Homebrew/test/support/helper/spec/shared_context/integration_test.rb

@@ -47,8 +47,7 @@ RSpec.shared_context "integration test" do
 
       example.run
     ensure
-      FileUtils.rm HOMEBREW_PREFIX/"bin/brew"
-      FileUtils.rmdir HOMEBREW_PREFIX/"bin"
+      FileUtils.rm_r HOMEBREW_PREFIX/"bin"
     end
   end
 

Library/Homebrew/test/system_command_spec.rb

@@ -23,7 +23,7 @@ describe SystemCommand do
         it "includes the given variables explicitly" do
           expect(Open3)
             .to receive(:popen3)
-            .with(an_instance_of(Hash), ["env", "env"], "A=1", "B=2", "C=3", "env", *env_args, {})
+            .with(an_instance_of(Hash), ["/usr/bin/env", "/usr/bin/env"], "A=1", "B=2", "C=3", "env", *env_args, {})
             .and_call_original
 
           command.run!
@@ -49,7 +49,7 @@ describe SystemCommand do
           expect(Open3)
             .to receive(:popen3)
             .with(an_instance_of(Hash), ["/usr/bin/sudo", "/usr/bin/sudo"], "-E", "--",
-                  "env", "A=1", "B=2", "C=3", "env", *env_args, {})
+                  "/usr/bin/env", "A=1", "B=2", "C=3", "env", *env_args, {})
             .and_wrap_original do |original_popen3, *_, &block|
               original_popen3.call("true", &block)
             end

Library/Homebrew/test/unpack_strategy/subversion_spec.rb

@@ -8,9 +8,8 @@ describe UnpackStrategy::Subversion, :needs_svn do
   let(:path) { working_copy }
 
   before do
-    system "svnadmin", "create", repo
-
-    system "svn", "checkout", "file://#{repo}", working_copy
+    safe_system "xcrun", "svnadmin", "create", repo
+    safe_system "svn", "checkout", "file://#{repo}", working_copy
 
     FileUtils.touch working_copy/"test"
     system "svn", "add", working_copy/"test"