Fix method name typo

Fix NoMethodError when using a union (||) of comparator sets. Add test to cover
that case and update comments.

Note SemanticPuppet incorrectly merges comparators sets with prerelease
versions. So it should consider 1.0.0 to be included in the range, but it is not
currently.

lib/semantic_puppet/version_range.rb

@@ -398,8 +398,8 @@ def upper_bound?
 
       # Merge two ranges so that the result matches the intersection of all matching versions.
       #
-      # @param range [AbastractRange] the range to intersect with
-      # @return [AbastractRange,nil] the intersection between the ranges
+      # @param range [AbstractRange] the range to intersect with
+      # @return [AbstractRange,nil] the intersection between the ranges
       #
       # @api private
       def intersection(range)
@@ -474,7 +474,7 @@ def merge(other)
             excl_end = other.exclude_end?
           else
             max = self.end
-            excl_end = exclude_end && other.exclude_end?
+            excl_end = exclude_end? && other.exclude_end?
           end
 
           MinMaxRange.create(excl_begin ? GtRange.new(min) : GtEqRange.new(min), excl_end ? LtRange.new(max) : LtEqRange.new(max))
@@ -499,7 +499,7 @@ def merge(other)
       # Checks if this matcher accepts a prerelease with the same major, minor, patch triple as the given version. Only matchers
       # where this has been explicitly stated will respond `true` to this method
       #
-      # @return [Boolean] `true` if this matcher accepts a prerelase with the tuple from the given version
+      # @return [Boolean] `true` if this matcher accepts a prerelease with the tuple from the given version
       def test_prerelease?(_)
         false
       end

spec/unit/semantic_puppet/version_range_spec.rb

@@ -270,6 +270,16 @@ def self.test_range(range_list, str, includes, excludes)
           expect(range.exclude_end?).to be_nil
         end
       end
+
+      context 'prerelease' do
+        test_expressions(
+          [ '>=5.0.1-rc0' || '>=0.5.0' ] => {
+            :to_str   => '>=5.0.1-rc0',
+            :includes => ['5.0.1-rc0', '5.0.1'], # should include 1.0.0
+            :excludes => ['1.0.0', '5.0.0-rc0', '5.0.2-rc0']
+          }
+        )
+      end
     end
 
     context 'invalid expressions' do