patch.diff

Index: ext/bigdecimal/bigdecimal.c
===================================================================
--- ext/bigdecimal/bigdecimal.c	(revision 45014)
+++ ext/bigdecimal/bigdecimal.c	(revision 45015)
@@ -2467,9 +2467,11 @@
 static VALUE
 BigDecimal_initialize(int argc, VALUE *argv, VALUE self)
 {
+    ENTER(1);
     Real *pv = rb_check_typeddata(self, &BigDecimal_data_type);
-    Real *x = BigDecimal_new(argc, argv);
+    Real *x;
 
+    GUARD_OBJ(x, BigDecimal_new(argc, argv));
     if (ToValue(x)) {
 	pv = VpCopy(pv, x);
     }
@@ -2548,7 +2550,10 @@
 static VALUE
 BigDecimal_global_new(int argc, VALUE *argv, VALUE self)
 {
-    Real *pv = BigDecimal_new(argc, argv);
+    ENTER(1);
+    Real *pv;
+
+    GUARD_OBJ(pv, BigDecimal_new(argc, argv));
     if (ToValue(pv)) pv = VpCopy(NULL, pv);
     pv->obj = TypedData_Wrap_Struct(rb_cBigDecimal, &BigDecimal_data_type, pv);
     return pv->obj;

USAGE.md

Read this rbenv/ruby-build#550 if you're trying to install patch on Mac OS X 10.9 with homebrew

rbenv install -f --patch 2.1.1 < <(curl -sSL https://gist.githubusercontent.com/TimothyKlim/11043852/raw/fe228cf0524873c992fa5c31b1173537dca76a2c/patch.diff)