Program: 86522
Project: 86522
Buggy source:
/** 
 * Appends the given qualifier suffix.  Attempts to match the given qualifier suffix to the current suffix to avoid duplicates like "1.0-beta-beta.  If the suffix matches the existing one, does nothing.
 * @param suffix The qualifier suffix to append. This can be a simple string like "foo", or it can optionallyinclude a build number, for example "foo-1", which will automatically be set as the build number for this version.
 */
public void appendQualifierSuffix(String suffix){
  logger.debug("String_Node_Str" + suffix + "String_Node_Str"+ getVersionString());
  if (suffix == null) {
    return;
  }
  Matcher snapshotMatcher=snapshotPattern.matcher(suffix);
  snapshotMatcher.matches();
  final String suffixWithoutSnapshot=snapshotMatcher.group(1);
  final String suffixSnapshotDelimiter=snapshotMatcher.group(2);
  final String suffixSnapshot=snapshotMatcher.group(3);
  if (!isEmpty(suffixSnapshot)) {
    this.snapshotDelimiter=suffixSnapshotDelimiter;
    this.snapshot=suffixSnapshot;
  }
  Matcher suffixMatcher=qualifierPattern.matcher(suffixWithoutSnapshot);
  if (!suffixMatcher.matches()) {
    return;
  }
  String suffixBase=suffixMatcher.group(1);
  String suffixBuildNumberDelimiter=suffixMatcher.group(3);
  String suffixBuildNumber=suffixMatcher.group(4);
  String suffixBaseNoDelim=this.removeLastDelimiters(suffixBase);
  String suffixMatchRegex="String_Node_Str" + Pattern.quote(suffixBaseNoDelim) + "String_Node_Str"+ DELIMITER_REGEX+ "String_Node_Str";
  String oldQualifierBase=getQualifierBase();
  String oldQualifierBaseAndNum=getQualifierBaseAndBuildNum();
  if (isEmpty(oldQualifierBaseAndNum)) {
    if (suffixBase.length() > 0 && versionStringDelimiters.contains(suffixBase.charAt(0))) {
      qualifierStartDelimiter=Character.toString(suffixBase.charAt(0));
      suffixBase=suffixBase.substring(1);
    }
    qualifierBase=suffixBase;
  }
 else   if (!Pattern.matches(suffixMatchRegex,oldQualifierBase)) {
    StringBuilder newQualifierBase=new StringBuilder(oldQualifierBaseAndNum);
    buildNumber=null;
    if (newQualifierBase.length() > 0 && !versionStringDelimiters.contains(newQualifierBase.charAt(newQualifierBase.length() - 1))) {
      newQualifierBase.append(DEFAULT_QUALIFIER_DELIMITER);
    }
    newQualifierBase.append(suffixBase);
    qualifierBase=newQualifierBase.toString();
  }
  if (!isEmpty(suffixBuildNumber)) {
    buildNumberDelimiter=suffixBuildNumberDelimiter;
    buildNumber=suffixBuildNumber;
  }
  logger.debug("String_Node_Str" + getVersionString());
}

Fixed version (ground truth):
/** 
 * Appends the given qualifier suffix.  Attempts to match the given qualifier suffix to the current suffix to avoid duplicates like "1.0-beta-beta.  If the suffix matches the existing one, does nothing.
 * @param suffix The qualifier suffix to append. This can be a simple string like "foo", or it can optionallyinclude a build number, for example "foo-1", which will automatically be set as the build number for this version.
 */
public void appendQualifierSuffix(String suffix){
  logger.debug("String_Node_Str" + suffix + "String_Node_Str"+ getVersionString());
  if (suffix == null) {
    return;
  }
  Matcher snapshotMatcher=snapshotPattern.matcher(suffix);
  snapshotMatcher.matches();
  final String suffixWithoutSnapshot=snapshotMatcher.group(1);
  final String suffixSnapshotDelimiter=snapshotMatcher.group(3);
  final String suffixSnapshot=snapshotMatcher.group(4);
  if (!isEmpty(suffixSnapshot)) {
    this.snapshotDelimiter=suffixSnapshotDelimiter;
    this.snapshot=suffixSnapshot;
  }
  Matcher suffixMatcher=qualifierPattern.matcher(suffixWithoutSnapshot);
  if (!suffixMatcher.matches()) {
    return;
  }
  String suffixBase=suffixMatcher.group(1);
  String suffixBuildNumberDelimiter=suffixMatcher.group(3);
  String suffixBuildNumber=suffixMatcher.group(4);
  String suffixBaseNoDelim=this.removeLastDelimiters(suffixBase);
  String suffixMatchRegex="String_Node_Str" + Pattern.quote(suffixBaseNoDelim) + "String_Node_Str"+ DELIMITER_REGEX+ "String_Node_Str";
  String oldQualifierBase=getQualifierBase();
  String oldQualifierBaseAndNum=getQualifierBaseAndBuildNum();
  if (isEmpty(oldQualifierBaseAndNum)) {
    if (suffixBase.length() > 0 && versionStringDelimiters.contains(suffixBase.charAt(0))) {
      qualifierStartDelimiter=Character.toString(suffixBase.charAt(0));
      suffixBase=suffixBase.substring(1);
    }
    qualifierBase=suffixBase;
  }
 else   if (!Pattern.matches(suffixMatchRegex,oldQualifierBase)) {
    StringBuilder newQualifierBase=new StringBuilder(oldQualifierBaseAndNum);
    buildNumber=null;
    if (newQualifierBase.length() > 0 && !versionStringDelimiters.contains(newQualifierBase.charAt(newQualifierBase.length() - 1))) {
      newQualifierBase.append(DEFAULT_QUALIFIER_DELIMITER);
    }
    newQualifierBase.append(suffixBase);
    qualifierBase=newQualifierBase.toString();
    buildNumberDelimiter=suffixBuildNumberDelimiter;
  }
  if (!isEmpty(suffixBuildNumber)) {
    if (suffixBuildNumberDelimiter == null) {
      buildNumberDelimiter="String_Node_Str";
    }
 else {
      buildNumberDelimiter=suffixBuildNumberDelimiter;
    }
    buildNumber=suffixBuildNumber;
  }
  logger.debug("String_Node_Str" + getVersionString());
}