Guile1.9.14 formatted output

[Fu-gangqiang]

Hi,all

my guile1.9.14 output like this:

when I studied the format procedure following the mannual:

====== mannual start=====

~f 
If overflowchar and width are both given and if the output would exceed width, then that many overflowchars are printed instead of the value.
               (format #t "~5,,,'xf" 12345) -| 12345
               (format #t "~4,,,'xf" 12345) -| xxxx           <- bug
====== mannual end=====but i got like this:

====== repl start=====

scheme@(guile-user)> (format #f "~5,,,'xf" 12345)
"xxxxx"
scheme@(guile-user)> (format #f "~6,,,'xf" 12345)
"12345."
====== repl end=====