Improve unit test

tests/fuzzer.c

@@ -2723,7 +2723,7 @@ static int basicUnitTests(U32 const seed, double compressibility)
         assert(cctx != NULL);
 
         /* Populate src with random data */
-        RDG_genBuffer(CNBuffer, srcSize, compressibility, 0., seed);
+        RDG_genBuffer(CNBuffer, srcSize, compressibility, 0.5, seed);
 
         /* Test with block delimiters roundtrip */
         seqsSize = ZSTD_generateSequences(cctx, seqs, srcSize, src, srcSize);