Remove special-case check on rare condition

A special case was checked that only occurs when calling uniform with a range of only one element. This was not necessary to keep the math correct and represented a slight slowdown in the common case for no apparent benefit.

std/random.d

@@ -1347,7 +1347,6 @@ if (isIntegral!(CommonType!(T1, T2)) || isSomeChar!(CommonType!(T1, T2)))
     }
 
     assert(upperDist != 0);
-    if (upperDist == 1) return lower;
 
     alias UpperType = typeof(upperDist);
     static assert(UpperType.min == 0);
@@ -1447,6 +1446,13 @@ unittest
         }
         assert(sawLB && sawUB);
     }
+
+    {
+        foreach (i; 0 .. 30)
+        {
+            assert(i == uniform(i, i+1, reproRng));
+        }
+    }
 }
 
 /**