Issue #19373: Apply upstream change to Tk 8.5.15 fixing OS X 10.9
screen refresh problem.
diff --git a/Mac/BuildScript/build-installer.py b/Mac/BuildScript/build-installer.py
index 69f3ff7..0859b3a 100755
--- a/Mac/BuildScript/build-installer.py
+++ b/Mac/BuildScript/build-installer.py
@@ -215,6 +215,9 @@
               name="Tk 8.5.15",
               url="ftp://ftp.tcl.tk/pub/tcl//tcl8_5/tk8.5.15-src.tar.gz",
               checksum='55b8e33f903210a4e1c8bce0f820657f',
+              patches=[
+                  "issue19373_tk_8_5_15_source.patch",
+                   ],
               buildDir="unix",
               configure_pre=[
                     '--enable-aqua',
@@ -797,8 +800,6 @@
 
     workDir = extractArchive(buildDir, sourceArchive)
     os.chdir(workDir)
-    if 'buildDir' in recipe:
-        os.chdir(recipe['buildDir'])
 
     for patch in recipe.get('patches', ()):
         if isinstance(patch, tuple):
@@ -825,6 +826,9 @@
         runCommand('sh %s' % shellQuote(fn))
         os.unlink(fn)
 
+    if 'buildDir' in recipe:
+        os.chdir(recipe['buildDir'])
+
     if configure is not None:
         configure_args = [
             "--prefix=/usr/local",