Support key swapping in Hash#transform_keys!.

This also updates Ruby compat version to run post-2.5.1 specs for
this behavior.

https://bugs.ruby-lang.org/issues/14380

core/pom.xml

@@ -61,10 +61,10 @@ DO NOT MODIFIY - GENERATED CODE
     <test.results.dir>${build.dir}/test-results</test.results.dir>
     <tzdata.scope>provided</tzdata.scope>
     <tzdata.version>2013d</tzdata.version>
-    <version.ruby>2.5.0</version.ruby>
+    <version.ruby>2.5.3</version.ruby>
     <version.ruby.major>2.5</version.ruby.major>
-    <version.ruby.minor>0</version.ruby.minor>
-    <version.ruby.revision>60928</version.ruby.revision>
+    <version.ruby.minor>3</version.ruby.minor>
+    <version.ruby.revision>66309</version.ruby.revision>
   </properties>
   <dependencies>
     <dependency>

core/src/main/java/org/jruby/RubyHash.java

@@ -1515,10 +1515,14 @@ public IRubyObject transform_values(final ThreadContext context, final Block blo
     public IRubyObject transform_keys_bang(final ThreadContext context, final Block block) {
         if (block.isGiven()) {
             testFrozen("Hash");
-            RubyArray keys = keys(context);
-            Arrays.stream(keys.toJavaArrayMaybeUnsafe()).forEach((key) -> {
-                op_aset(context, block.yield(context, key), delete(context, key));
-            });
+            RubyArray pairs = (RubyArray) flatten(context);
+            clear();
+            for (int i = 0; i < pairs.size(); i += 2) {
+                IRubyObject key = pairs.eltOk(i);
+                IRubyObject newKey = block.yield(context, key);
+                IRubyObject value = pairs.eltOk(i + 1);
+                op_aset(context, newKey, value);
+            }
             return this;
         }
 

default.build.properties

@@ -34,7 +34,7 @@ rake.args=
 install4j.executable=/Applications/install4j7/bin/install4jc
 
 # Ruby versions
-version.ruby=2.5.0
+version.ruby=2.5.3
 version.ruby.major=2.5
-version.ruby.minor=0
-version.ruby.revision=60928
+version.ruby.minor=3
+version.ruby.revision=66309