ccache changes file permissions unexpectedly

After the software upgrade I noticed my IDE cannot compile a project
after it was built from the terminal. It turned out that build
directory now contains objects with such strange permissions:

-r--r--r--

When I removed ccache from the compiling command it created normal rw
files. My umask is 0002

I suspected it is because of the new `umask` setting in ccache which
works differently by default (which is a really bad design choice).
`ccache -p` printed just an empty value for that setting. Setting it
to 0002 and clearing it with `ccache -C` didn't help anything. So, how
it works now and how to get it back to human-expected behaviour?

ccache version 4.5.1

-- 
@midenok