updated for version 7.3.802
Problem:    After setting 'isk' to a value ending in a comma appending to the
            option fails.
Solution:   Disallow a trailing comma for 'isk' and similar options.
diff --git a/src/charset.c b/src/charset.c
index b5dcfac..fd4b500 100644
--- a/src/charset.c
+++ b/src/charset.c
@@ -284,7 +284,12 @@
 		}
 		++c;
 	    }
+
+	    c = *p;
 	    p = skip_to_option_part(p);
+	    if (c == ',' && *p == NUL)
+		/* Trailing comma is not allowed. */
+		return FAIL;
 	}
     }
     chartab_initialized = TRUE;