[ccache] ccache trying to update cache in read-only mode

[ganesh subramonian]

Hi,

I am using ccache-3.2.4 in an environment like this.
A cron job writes to ccache every 12 hours.
All
 others run ccache with read_only mode. I see that ccache is failing 
quite often when it is trying to copy files to the cache directory 
(which is read-only for my user).
Adding logs to ccache code I see the call is happening from:

    if (generating_dependencies && mode == FROMCACHE_CPP_MODE) {
        put_file_in_cache(output_dep, cached_dep);
    }

Shouldn't put_file_in_cache have a check for conf->read_only


thanks
Ganesh