patch 8.0.1837: one character cmdline abbreviation not triggered after '<,'>

Problem:    One character cmdline abbreviation not triggered after '<,'>.
Solution:   Skip over the special range. (Christian Brabandt, closes #2320)
diff --git a/src/ex_getln.c b/src/ex_getln.c
index 0124098..acaaef4 100644
--- a/src/ex_getln.c
+++ b/src/ex_getln.c
@@ -3572,10 +3572,25 @@
     static int
 ccheck_abbr(int c)
 {
+    int spos = 0;
+
     if (p_paste || no_abbr)	    /* no abbreviations or in paste mode */
 	return FALSE;
 
-    return check_abbr(c, ccline.cmdbuff, ccline.cmdpos, 0);
+    /* Do not consider '<,'> be part of the mapping, skip leading whitespace.
+     * Actually accepts any mark. */
+    while (VIM_ISWHITE(ccline.cmdbuff[spos]) && spos < ccline.cmdlen)
+	spos++;
+    if (ccline.cmdlen - spos > 5
+	    && ccline.cmdbuff[spos] == '\''
+	    && ccline.cmdbuff[spos + 2] == ','
+	    && ccline.cmdbuff[spos + 3] == '\'')
+	spos += 5;
+    else
+	/* check abbreviation from the beginning of the commandline */
+	spos = 0;
+
+    return check_abbr(c, ccline.cmdbuff, ccline.cmdpos, spos);
 }
 
 #if defined(FEAT_CMDL_COMPL) || defined(PROTO)