Revert r63934 -- it was mixing two patches.
diff --git a/Modules/main.c b/Modules/main.c
index e2bfdb4..b762b0f 100644
--- a/Modules/main.c
+++ b/Modules/main.c
@@ -72,6 +72,7 @@
 -OO    : remove doc-strings in addition to the -O optimizations\n\
 -s     : don't add user site directory to sys.path; also PYTHONNOUSERSITE\n\
 -S     : don't imply 'import site' on initialization\n\
+-t     : issue warnings about inconsistent tab usage (-tt: issue errors)\n\
 ";
 static char *usage_3 = "\
 -u     : unbuffered binary stdout and stderr; also PYTHONUNBUFFERED=x\n\
@@ -369,7 +370,7 @@
 			break;
 
 		case 't':
-			/* ignored for backwards compatibility */
+			Py_TabcheckFlag++;
 			break;
 
 		case 'u':