Program: 101571
Project: 101571
Buggy source:
/** 
 * Compute a list of patches to turn text1 into text2. Use the diffs provided.
 * @param source Old text
 * @param target New text
 * @param diffs Optional array of diff tuples for text1 to text2.
 * @return this patch
 */
public Patch make(String source,String target,List diffList){
  List diffs=diffList;
  if (diffs == null) {
    Diff diff=new Diff(source,target);
    diffs=diff.compare();
    if (diffs.size() > 2) {
      DiffCleanup.cleanupSemantic(diffs);
      DiffCleanup.cleanupEfficiency(diffs);
    }
  }
  patches.clear();
  if (diffs.size() == 0) {
    return this;
  }
  PatchEntry patch=new PatchEntry();
  int charCount1=0;
  int charCount2=0;
  String prePatchText=source;
  String postPatchText=source;
  Iterator iter=diffs.iterator();
  int x=0;
  while (iter.hasNext()) {
    Difference diff=(Difference)iter.next();
    EditType editType=diff.getEditType();
    String diffText=diff.getText();
    int len=diffText.length();
    if (!patch.hasDifferences() && !EditType.EQUAL.equals(editType)) {
      patch.setSourceStart(charCount1);
      patch.setTargetStart(charCount2);
    }
    if (EditType.INSERT.equals(editType)) {
      patch.addDifference(diff);
      patch.adjustTargetLength(len);
      postPatchText=postPatchText.substring(0,charCount2) + diffText + postPatchText.substring(charCount2);
    }
 else     if (EditType.DELETE.equals(editType)) {
      patch.adjustSourceLength(len);
      patch.addDifference(diff);
      postPatchText=postPatchText.substring(0,charCount2) + postPatchText.substring(charCount2 + len);
    }
 else     if (EditType.EQUAL.equals(editType) && len <= 2 * margin && patch.hasDifferences() && diffs.size() != x + 1) {
      patch.addDifference(diff);
      patch.adjustSourceLength(len);
      patch.adjustTargetLength(len);
    }
    if (EditType.EQUAL.equals(editType) && len >= 2 * margin && patch.hasDifferences()) {
      patch.addContext(prePatchText);
      patches.add(patch);
      patch=new PatchEntry();
      prePatchText=postPatchText;
    }
    if (!EditType.INSERT.equals(editType)) {
      charCount1+=len;
    }
    if (!EditType.DELETE.equals(editType)) {
      charCount2+=len;
    }
    x++;
  }
  if (patch.hasDifferences()) {
    patch.addContext(prePatchText);
    patches.add(patch);
  }
  return this;
}

Fixed version (ground truth):
/** 
 * Compute a list of patches to turn text1 into text2. Use the diffs provided.
 * @param source Old text
 * @param target New text
 * @param diffList Optional array of diff tuples for text1 to text2.
 * @return this patch
 */
public Patch make(String source,String target,List diffList){
  List diffs=diffList;
  if (diffs == null) {
    Diff diff=new Diff(source,target);
    diffs=diff.compare();
    if (diffs.size() > 2) {
      DiffCleanup.cleanupSemantic(diffs);
      DiffCleanup.cleanupEfficiency(diffs);
    }
  }
  patches.clear();
  if (diffs.size() == 0) {
    return this;
  }
  PatchEntry patch=new PatchEntry();
  int charCount1=0;
  int charCount2=0;
  String prePatchText=source;
  String postPatchText=source;
  Iterator iter=diffs.iterator();
  int x=0;
  while (iter.hasNext()) {
    Difference diff=(Difference)iter.next();
    EditType editType=diff.getEditType();
    String diffText=diff.getText();
    int len=diffText.length();
    if (!patch.hasDifferences() && !EditType.EQUAL.equals(editType)) {
      patch.setSourceStart(charCount1);
      patch.setTargetStart(charCount2);
    }
    if (EditType.INSERT.equals(editType)) {
      patch.addDifference(diff);
      patch.adjustTargetLength(len);
      postPatchText=postPatchText.substring(0,charCount2) + diffText + postPatchText.substring(charCount2);
    }
 else     if (EditType.DELETE.equals(editType)) {
      patch.adjustSourceLength(len);
      patch.addDifference(diff);
      postPatchText=postPatchText.substring(0,charCount2) + postPatchText.substring(charCount2 + len);
    }
 else     if (EditType.EQUAL.equals(editType) && len <= 2 * margin && patch.hasDifferences() && diffs.size() != x + 1) {
      patch.addDifference(diff);
      patch.adjustSourceLength(len);
      patch.adjustTargetLength(len);
    }
    if (EditType.EQUAL.equals(editType) && len >= 2 * margin && patch.hasDifferences()) {
      patch.addContext(prePatchText);
      patches.add(patch);
      patch=new PatchEntry();
      prePatchText=postPatchText;
    }
    if (!EditType.INSERT.equals(editType)) {
      charCount1+=len;
    }
    if (!EditType.DELETE.equals(editType)) {
      charCount2+=len;
    }
    x++;
  }
  if (patch.hasDifferences()) {
    patch.addContext(prePatchText);
    patches.add(patch);
  }
  return this;
}