Ensure we don't find breaks in api dependencies needlessly (#238)

Fixes a bug introduced in 1.3.2 where breaks for `api` dependencies would be spuriously reported.

Author: CRogers

changelog/@unreleased/pr-238.v2.yml

@@ -0,0 +1,6 @@
+type: fix
+fix:
+  description: Fixes a bug introduced in 1.3.2 where breaks for `api` dependencies
+    would be spuriously reported.
+  links:
+  - https://github.com/palantir/gradle-revapi/pull/238

src/main/java/com/palantir/gradle/revapi/ResolveOldApi.java

@@ -102,7 +102,7 @@ private static OldApi resolveOldApiWithVersion(Project project, GroupNameVersion
         Set<File> oldWithDeps = OldApiConfigurations.resolveOldConfiguration(project, groupNameVersion, true);
 
         Set<File> oldJustDeps = new HashSet<>(oldWithDeps);
-        oldJustDeps.removeAll(oldWithDeps);
+        oldJustDeps.removeAll(oldOnlyJar);
 
         return OldApi.builder().jars(oldOnlyJar).dependencyJars(oldJustDeps).build();
     }

src/test/groovy/com/palantir/gradle/revapi/RevapiSpec.groovy

@@ -569,6 +569,47 @@ class RevapiSpec extends IntegrationSpec {
         println runTasksSuccessfully("revapi").standardOutput
     }
 
+    def 'should not say there are breaks in api dependencies when nothing has changed'() {
+        when:
+        rootProjectNameIs('test')
+
+        buildFile << """
+            apply plugin: '${TestConstants.PLUGIN_NAME}'
+            apply plugin: 'java-library'
+            apply plugin: 'maven-publish'
+
+            group = 'revapi'
+            version = '1.0.0'
+            
+            repositories {
+                mavenCentral()
+            }
+            ${mavenRepoGradle()}
+
+            ${testMavenPublication()}
+
+            dependencies {
+                api 'junit:junit:4.12'
+            }
+
+            revapi {
+                oldVersion = project.version
+            }
+        """.stripIndent()
+
+        writeToFile 'src/main/java/foo/Foo.java', '''
+            package foo;
+            // Use an junit interface in our public api so revapi cares about it 
+            public interface Foo extends org.junit.rules.TestRule { }
+        '''
+
+        and:
+        println runTasksSuccessfully("publish").standardOutput
+
+        then:
+        println runTasksSuccessfully("revapi").standardOutput
+    }
+
     def 'ignores scala classes'() {
         when:
         buildFile << """