Make sure Redis does not reply with negative zero

src/util.c

@@ -560,6 +560,10 @@ int ld2string(char *buf, size_t len, long double value, ld2string_mode mode) {
                 }
                 if (*p == '.') l--;
             }
+            if (l == 2 && buf[0] == '-' && buf[1] == '0') {
+                buf[0] = '0';
+                l = 1;
+            }
             break;
         default: return 0; /* Invalid mode. */
         }

tests/unit/type/incr.tcl

@@ -151,4 +151,10 @@ start_server {tags {"incr"}} {
         catch {r incrbyfloat foo 1} err
         format $err
     } {ERR*valid*}
+
+    test {No negative zero} {
+        r incrbyfloat foo [expr double(1)/41]
+        r incrbyfloat foo [expr double(-1)/41]
+        r get foo
+    } {0}
 }