termio: clear screen always sends form feed (0x0C)

Fixes #555

src/termio/Exec.zig

@@ -379,20 +379,12 @@ pub fn clearScreen(self: *Exec, history: bool) !void {
         // Clear our scrollback
         if (history) try self.terminal.screen.clear(.history);
 
-        // If we're not at a prompt, we clear the screen manually using
-        // the terminal screen state. If we are at a prompt, we send
-        // form-feed so that the shell can repaint the entire screen.
-        if (!self.terminal.cursorIsAtPrompt()) {
-            // Clear above the cursor
+        // Clear our screen using terminal state.
         try self.terminal.screen.clear(.above_cursor);
-
-            // Exit
-            return;
-        }
     }
 
-    // If we reached here it means we're at a prompt, so we send a form-feed.
-    assert(self.terminal.cursorIsAtPrompt());
+    // We also always send form feed so that the terminal can repaint
+    // our prompt.
     try self.queueWrite(&[_]u8{0x0C});
 }