Revert note about signum of NaN

library/core/src/num/f128.rs

@@ -594,7 +594,7 @@ impl f128 {
     /// conserved over arithmetic operations, the result of `is_sign_positive` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// #![feature(f128)]
@@ -620,7 +620,7 @@ impl f128 {
     /// conserved over arithmetic operations, the result of `is_sign_negative` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// #![feature(f128)]

library/core/src/num/f16.rs

@@ -588,7 +588,7 @@ impl f16 {
     /// conserved over arithmetic operations, the result of `is_sign_positive` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// #![feature(f16)]
@@ -616,7 +616,7 @@ impl f16 {
     /// conserved over arithmetic operations, the result of `is_sign_negative` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// #![feature(f16)]

library/core/src/num/f32.rs

@@ -811,7 +811,7 @@ impl f32 {
     /// conserved over arithmetic operations, the result of `is_sign_positive` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// let f = 7.0_f32;
@@ -836,7 +836,7 @@ impl f32 {
     /// conserved over arithmetic operations, the result of `is_sign_negative` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// let f = 7.0f32;

library/core/src/num/f64.rs

@@ -810,7 +810,7 @@ impl f64 {
     /// conserved over arithmetic operations, the result of `is_sign_positive` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == 1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// let f = 7.0_f64;
@@ -835,7 +835,7 @@ impl f64 {
     /// conserved over arithmetic operations, the result of `is_sign_negative` on
     /// a NaN might produce an unexpected or non-portable result. See the [specification
     /// of NaN bit patterns](f32#nan-bit-patterns) for more info. Use `self.signum() == -1.0`
-    /// if you need fully portable behavior (will return NaN for all NaNs).
+    /// if you need fully portable behavior (evaluates to `false` for all NaNs).
     ///
     /// ```
     /// let f = 7.0_f64;