Allow building insignificant when normal claimed

On top of already allowing a rebuild of a tagged version that's already
claimed, we should allow rebuilding insignificant versions.

As noted in the issue, this allows use of git bisect on reckoned repos.

This fixes #78.

reckon-core/src/main/java/org/ajoberstar/reckon/core/Reckoner.java

@@ -35,7 +35,7 @@ private Reckoner(VcsInventorySupplier inventorySupplier, Function<VcsInventory,
 
   /**
    * Infers the version that reflects the current state of your repository.
-   * 
+   *
    * @return the reckoned version
    */
   public Version reckon() {
@@ -47,6 +47,10 @@ public Version reckon() {
       throw new IllegalStateException("Reckoned version " + reckoned + " has already been released.");
     }
 
+    if (inventory.getClaimedVersions().contains(targetNormal) && !inventory.getCurrentVersion().filter(targetNormal::equals).isPresent() && reckoned.isSignificant()) {
+      throw new IllegalStateException("Reckoned target normal version " + targetNormal + " has already been released.");
+    }
+
     if (inventory.getBaseVersion().compareTo(reckoned) > 0) {
       throw new IllegalStateException("Reckoned version " + reckoned + " is (and cannot be) less than base version " + inventory.getBaseVersion());
     }
@@ -78,10 +82,6 @@ private Version reckonNormal(VcsInventory inventory) {
       targetNormal = targetNormal.incrementNormal(scope);
     }
 
-    if (inventory.getClaimedVersions().contains(targetNormal) && !inventory.getCurrentVersion().filter(targetNormal::equals).isPresent()) {
-      throw new IllegalStateException("Reckoned target normal version " + targetNormal + " has already been released.");
-    }
-
     return targetNormal;
   }
 
@@ -147,7 +147,7 @@ Builder vcs(VcsInventorySupplier inventorySupplier) {
 
     /**
      * Use the given JGit repository to infer the state of Git.
-     * 
+     *
      * @param repo repository that the version should be inferred from
      * @return this builder
      */
@@ -162,7 +162,7 @@ public Builder git(Repository repo) {
 
     /**
      * Use the given function to determine what scope should be used when inferring the version.
-     * 
+     *
      * @param scopeCalc the function that provides the scope
      * @return this builder
      */
@@ -173,7 +173,7 @@ public Builder scopeCalc(Function<VcsInventory, Optional<String>> scopeCalc) {
 
     /**
      * Use the given stages as valid options during inference.
-     * 
+     *
      * @param stages the valid stages
      * @return this builder
      */
@@ -189,7 +189,7 @@ public Builder stages(String... stages) {
 
     /**
      * Use only the {@code snapshot} and {@code final} stages. Alternative to calling {@code stages()}.
-     * 
+     *
      * @return this builder
      */
     public Builder snapshots() {
@@ -201,7 +201,7 @@ public Builder snapshots() {
     /**
      * Use the given function to determine what staged should be used when inferring the version. This
      * must return a version contained in {@code stages()}.
-     * 
+     *
      * @param stageCalc the function that provides the stage
      * @return this builder
      */
@@ -212,7 +212,7 @@ public Builder stageCalc(BiFunction<VcsInventory, Version, Optional<String>> sta
 
     /**
      * Builds the reckoner.
-     * 
+     *
      * @return the reckoner
      */
     public Reckoner build() {

reckon-core/src/test/groovy/org/ajoberstar/reckon/core/ReckonerTest.groovy

@@ -189,6 +189,40 @@ class ReckonerTest extends Specification {
     reckonStage(inventory, null, null) == '0.1.0'
   }
 
+   def 'if target normal claimed, but building insignificant, succeed'() {
+    given:
+    def inventory = new VcsInventory(
+      'abcdef',
+      true,
+      null,
+      Version.valueOf('0.0.0'),
+      Version.valueOf('0.0.0'),
+      1,
+      [] as Set,
+      [Version.valueOf('0.1.0'), Version.valueOf('0.1.1'), Version.valueOf('0.2.0')] as Set
+      )
+    expect:
+    reckonStage(inventory, null, null) == '0.1.0-beta.0.1+abcdef'
+  }
+
+  def 'if target normal claimed, and building significant, throw'() {
+    given:
+    def inventory = new VcsInventory(
+      'abcdef',
+      true,
+      null,
+      Version.valueOf('0.0.0'),
+      Version.valueOf('0.0.0'),
+      1,
+      [] as Set,
+      [Version.valueOf('0.1.0'), Version.valueOf('0.1.1'), Version.valueOf('0.2.0')] as Set
+      )
+    when:
+    reckonStage(inventory, null, 'rc')
+    then:
+    thrown(IllegalStateException)
+  }
+
   def 'if scope supplier returns invalid scope, throw'() {
     given:
     def inventory = new VcsInventory(