Add comment and test case

src/value.cpp

@@ -410,6 +410,7 @@ namespace Exiv2 {
     int AsciiValue::read(const std::string& buf)
     {
         value_ = buf;
+        // ensure count>0 and nul terminated # https://github.com/Exiv2/exiv2/issues/1484
         if (value_.size() == 0 || value_[value_.size()-1] != '\0') value_ += '\0';
         return 0;
     }

tests/bugfixes/github/test_issue_1484.py

@@ -0,0 +1,16 @@
+# -*- coding: utf-8 -*-
+
+from system_tests import CaseMeta, CopyTmpFiles, path
+@CopyTmpFiles("$data_path/Stonehenge.exv")
+
+class test_issue_1484(metaclass=CaseMeta):
+    url       = "https://github.com/Exiv2/exiv2/issues/1484"
+    filename  = path("$tmp_path/Stonehenge.exv")
+    commands  = [ "$exiv2 -g Copyright                            $filename" 
+                , "$exiv2 -M\"set Exif.Image.Copyright Ascii ''\" $filename"
+                , "$exiv2 -g Copyright                            $filename"
+                ]
+    stdout   =  ["","","""Exif.Image.Copyright                         Ascii       1  
+"""]
+    stderr = [""]*len(commands)
+    retval = [ 1,0,0]