sysinstall: suppress 'no' prompt to begin installation

The user has to type 'yes', but it doesn't mean that the default of
'no' is ever useful. Suppress it, so the user doesn't have to press
backspace twice.

src/cryptenroll/cryptenroll-interactive.c

@@ -151,7 +151,7 @@ static int ask_wipe(EnrollContext *c, unsigned existing_mask) {
                         return log_oom();
 
                 bool wipe;
-                r = prompt_loop_yes_no(question, /* def= */ false, &wipe);
+                r = prompt_loop_yes_no(question, "no", /* def= */ false, &wipe);
                 if (r < 0)
                         return r;
 

src/shared/prompt-util.c

@@ -217,19 +217,19 @@ static int boolean_is_valid(const char *name, void *userdata) {
         return parse_boolean(name) >= 0;
 }
 
-int prompt_loop_yes_no(const char *question, bool def, bool *ret) {
+int prompt_loop_yes_no(const char *question, const char *prefill, bool def, bool *ret) {
         int r;
 
         assert(question);
         assert(ret);
 
-        char **l = STRV_MAKE("yes", "no");
+        char **menu = STRV_MAKE("yes", "no");
 
         _cleanup_free_ char *reply = NULL;
         r = prompt_loop(question,
                         GLYPH_WARNING_SIGN,
-                        /* prefill= */ def ? "yes" : "no",
-                        /* menu= */ l,
+                        /* prefill= */ prefill,
+                        /* menu= */ menu,
                         /* accepted= */ NULL,
                         /* ellipsize_percentage= */ 20,
                         /* n_columns= */ 2,

src/shared/prompt-util.h

@@ -26,7 +26,7 @@ int prompt_loop(const char *text,
                 PromptFlags flags,
                 char **ret);
 
-int prompt_loop_yes_no(const char *question, bool def, bool *ret);
+int prompt_loop_yes_no(const char *question, const char *prefill, bool def, bool *ret);
 
 int chrome_show(const char *top, const char *bottom);
 void chrome_hide(void);

src/sysinstall/sysinstall.c

@@ -903,6 +903,7 @@ static int prompt_confirm(void) {
         bool yes;
         r = prompt_loop_yes_no(arg_summary ? "Please type 'yes' to confirm the choices above and begin the installation" :
                                              "Please type 'yes' to begin the installation",
+                               /* prefill= */ NULL,
                                /* def= */ false,
                                &yes);
         if (r < 0)