use workaround an upstream bug in version range

fixes #328

Author: mkristian

jruby-gradle-base-plugin/src/main/groovy/com/github/jrubygradle/internal/GemVersion.groovy

@@ -67,6 +67,8 @@ class GemVersion {
      * @param String version
      */
     GemVersion(String version) {
+        // workaround a bug in gem proxy which can not handle != operators
+        version = version.replace('=', '')
         if (version.contains('+')) {
             low = ZEROS.matcher(PLUS.matcher(DOT_PLUS.matcher(version).replaceFirst('.0')).replaceFirst('')).replaceFirst('')
             high = DIGITS_PLUS.matcher(DOT_PLUS.matcher(version).replaceFirst('.99999')).replaceFirst(MAX_VERSION)

jruby-gradle-base-plugin/src/test/groovy/com/github/jrubygradle/internal/GemVersionSpec.groovy

@@ -163,14 +163,22 @@ class GemVersionSpec extends Specification {
         subject.intersect('[0,)').toString() == '[0.9,0.9.99999]'
     }
 
-    def "intersects two versions special one"() {
+    def "intersects two versions with special full range"() {
         given:
         GemVersion subject = new GemVersion('[0,)')
 
         expect:
         subject.intersect('[0.9.0,0.9.99999]').toString() == '[0.9,0.9.99999]'
     }
 
+    def "intersects two versions with workaround due to upstream bug"() {
+        given:
+        GemVersion subject = new GemVersion('(=2.5.1.1,99999)')
+
+        expect:
+        subject.intersect('(=2.5.1.1,)').toString() == '(2.5.1.1,99999)'
+    }
+
     def "intersects with conflict"() {
         given:
         GemVersion subject = new GemVersion('[1.2.1, 1.2.3]')