#
#
# patch "diff_patch.cc"
#  from [9683e035dc2e1ab8d9dd17a002ab808e5b40d792]
#    to [2d75afbcc07d318c789eaf3697f46821e7d1de62]
# 
# patch "tests/calculation_of_unidiffs_start_of_file/__driver__.lua"
#  from [10acd94d2d039e77061d78040e0761a7774055d1]
#    to [942ae4233f2927b43f5cb2ddb4f8e0d145881871]
#
============================================================
--- diff_patch.cc	9683e035dc2e1ab8d9dd17a002ab808e5b40d792
+++ diff_patch.cc	2d75afbcc07d318c789eaf3697f46821e7d1de62
@@ -1128,12 +1128,12 @@ void unidiff_hunk_writer::advance_to(siz
 
 void unidiff_hunk_writer::advance_to(size_t newpos)
 {
-  if (a_begin + a_len + (2 * ctx) < newpos)
+  if (a_begin + a_len + (2 * ctx) < newpos || hunk.empty())
     {
       flush_hunk(newpos);
 
       // insert new leading context
-      if (newpos - ctx < a.size())
+      if (newpos < a.size() + ctx)
         {
           for (size_t i = ctx; i > 0; --i)
             {
============================================================
--- tests/calculation_of_unidiffs_start_of_file/__driver__.lua	10acd94d2d039e77061d78040e0761a7774055d1
+++ tests/calculation_of_unidiffs_start_of_file/__driver__.lua	942ae4233f2927b43f5cb2ddb4f8e0d145881871
@@ -21,7 +21,7 @@ rename("monodiff", "stdin")
 
 -- see if patch likes that
 rename("monodiff", "stdin")
-xfail({"patch", "firstfile"}, 0, false, false, true)
+check({"patch", "firstfile"}, 0, false, false, true)
 
 -- see if the resulting file has been properly patched
 check(samefile("firstfile", "secondfile"))