patch 7.4.2230
Problem:    There is no equivalent of 'smartcase' for a tag search.
Solution:   Add value "followscs" and "smart" to 'tagcase'. (Christian
            Brabandt, closes #712) Turn tagcase test into new style.
diff --git a/src/search.c b/src/search.c
index 1f1ba6a..6e3850d 100644
--- a/src/search.c
+++ b/src/search.c
@@ -367,9 +367,18 @@
     int
 ignorecase(char_u *pat)
 {
-    int		ic = p_ic;
+    return ignorecase_opt(pat, p_ic, p_scs);
+}
 
-    if (ic && !no_smartcase && p_scs
+/*
+ * As ignorecase() put pass the "ic" and "scs" flags.
+ */
+    int
+ignorecase_opt(char_u *pat, int ic_in, int scs)
+{
+    int		ic = ic_in;
+
+    if (ic && !no_smartcase && scs
 #ifdef FEAT_INS_EXPAND
 				&& !(ctrl_x_mode && curbuf->b_p_inf)
 #endif