patch 9.0.1044: setting window height using Python may cause errors

Problem:    Setting window height using Python may cause errors.
Solution:   When setting "curwin" also set "curbuf". (closes #11687)
diff --git a/src/if_py_both.h b/src/if_py_both.h
index 8dd7f09..110de23 100644
--- a/src/if_py_both.h
+++ b/src/if_py_both.h
@@ -4081,10 +4081,12 @@
 #endif
 	savewin = curwin;
 	curwin = self->win;
+	curbuf = curwin->w_buffer;
 
 	VimTryStart();
 	win_setheight((int) height);
 	curwin = savewin;
+	curbuf = curwin->w_buffer;
 	if (VimTryEnd())
 	    return -1;
 
@@ -4103,10 +4105,12 @@
 #endif
 	savewin = curwin;
 	curwin = self->win;
+	curbuf = curwin->w_buffer;
 
 	VimTryStart();
 	win_setwidth((int) width);
 	curwin = savewin;
+	curbuf = curwin->w_buffer;
 	if (VimTryEnd())
 	    return -1;