[devel] Prevent png_push_crc_skip() from hanging while reading an unknown chunk

or an over-large compressed zTXt chunk with the progressive reader.
diff --git a/CHANGES b/CHANGES
index 6af131f..e49f36e 100644
--- a/CHANGES
+++ b/CHANGES
@@ -3176,6 +3176,8 @@
     changed exp() back to png_exp().
 
 Version 1.5.1beta06 [January 16, 2011]
+  Prevent png_push_crc_skip() from hanging while reading an unknown chunk
+    or an over-large compressed zTXT chunk with the progressive reader.
 
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