fix(update): move Windows binary via absolute path

pkg/commands/update/root.go

@@ -130,24 +130,31 @@ func (c *RootCommand) Exec(_ io.Reader, out io.Writer) error {
 		return fmt.Errorf("error determining absolute target path: %w", err)
 	}
 
-	// Windows does not permit removing a running executable, however it will
-	// permit renaming it! So we first rename the running executable and then we
-	// move the executable that we downloaded to the same location as the
-	// original executable (which is allowed since we first renamed the running
-	// executable).
+	// Windows does not permit replacing a running executable (see next condition),
+	// however it will permit it if you first move the original executable.
+	// So we first move the running executable to a new location, then we move the
+	// executable that we downloaded to the same location as the original.
 	//
 	// Reference:
 	// https://github.com/golang/go/issues/21997#issuecomment-331744930
 	if fstruntime.Windows {
-		if err := os.Rename(execPath, execPath+"~"); err != nil {
+		if err := os.Rename(currentPath, currentPath+".bak"); err != nil {
 			c.Globals.ErrLog.Add(err)
-			if err = os.Remove(execPath + "~"); err != nil {
+			if err = os.Remove(currentPath + ".bak"); err != nil {
 				c.Globals.ErrLog.Add(err)
 			}
 		}
 	}
 
+	// Move the downloaded binary to the same location as the current binary.
 	if err := os.Rename(tmpBin, currentPath); err != nil {
+		c.Globals.ErrLog.AddWithContext(err, map[string]any{
+			"Executable (source)":      tmpBin,
+			"Executable (destination)": currentPath,
+		})
+		renameErr := err
+
+		// Failing that we'll try to io.Copy downloaded binary to the current binary.
 		if err := filesystem.CopyFile(tmpBin, currentPath); err != nil {
 			c.Globals.ErrLog.AddWithContext(err, map[string]any{
 				"Executable (source)":      tmpBin,
@@ -160,7 +167,7 @@ func (c *RootCommand) Exec(_ io.Reader, out io.Writer) error {
 				return spinErr
 			}
 
-			return fmt.Errorf("error moving latest binary in place: %w", err)
+			return fmt.Errorf("error 'copying' latest binary in place: %w (following an error 'moving': %w)", err, renameErr)
 		}
 	}