Fix test_build_error_color after emscripten-core#24804 (emscripten-core#24810)

My own fault for not waiting for the full CI run to complete.

Fixing the test also revealed a bug.  Doh!

Author: sbc100

test/test_other.py

@@ -12377,7 +12377,8 @@ def test_build_error_color(self):
     returncode, output = self.run_on_pty([EMCC, 'src.c'])
     self.assertNotEqual(returncode, 0)
     self.assertIn(b"\x1b[1msrc.c:1:13: \x1b[0m\x1b[0;1;31merror: \x1b[0m\x1b[1mexpected '}'\x1b[0m", output)
-    self.assertIn(b"\x1b[31merror: ", output)
+    # Verify that emcc errors show up as red and bold
+    self.assertIn(b"emcc: \x1b[31m\x1b[1m", output)
 
   @parameterized({
     'fno_diagnostics_color': ['-fno-diagnostics-color'],

tools/diagnostics.py

@@ -114,7 +114,7 @@ def reset_color_windows():
 def output_color(color):
   if WINDOWS:
     return output_color_windows(color)
-  return '\033[1m\033[3%sm' % color
+  return '\033[3%sm' % color
 
 
 def bold():