patch 9.0.0285: it is not easy to change the command line from a plugin
Problem: It is not easy to change the command line from a plugin.
Solution: Add setcmdline(). (Shougo Matsushita, closes #10869)
diff --git a/src/proto/ex_getln.pro b/src/proto/ex_getln.pro
index bcc310c..2eb32ab 100644
--- a/src/proto/ex_getln.pro
+++ b/src/proto/ex_getln.pro
@@ -34,6 +34,8 @@
void f_getcmdline(typval_T *argvars, typval_T *rettv);
void f_getcmdpos(typval_T *argvars, typval_T *rettv);
void f_getcmdscreenpos(typval_T *argvars, typval_T *rettv);
+int set_cmdline_str(char_u *str, int pos);
+void f_setcmdline(typval_T *argvars, typval_T *rettv);
void f_setcmdpos(typval_T *argvars, typval_T *rettv);
void f_getcmdtype(typval_T *argvars, typval_T *rettv);
int get_cmdline_firstc(void);