ceph: fix build, 12.2.2 -> 12.2.7

Since 772eef91686974b7710081a9a77e5c0e287c25e8, Boost
doesn't support by python by default, which broke ceph.

Also bump to 12.2.7, the latest release of ceph 12.

pkgs/tools/filesystems/ceph/default.nix

···
 { callPackage, fetchgit, fetchpatch, ... } @ args:
 
 callPackage ./generic.nix (args // rec {
-  version = "12.2.2";
+  version = "12.2.7";
 
   src = fetchgit {
     url = "https://github.com/ceph/ceph.git";
     rev = "refs/tags/v${version}";
-    sha256 = "01anqxyffa8l2lzgyb0dj6fjicfjdx2cq9y1klh24x69gxwkdh00";
+    sha256 = "031nfw2g2fdpxxx39g862phgmdx68hj9r54axazandghfhc1bzrl";
   };
 
 })

pkgs/top-level/all-packages.nix

···
   nrg2iso = callPackage ../tools/cd-dvd/nrg2iso { };
 
   libceph = ceph.lib;
-  ceph = callPackage ../tools/filesystems/ceph { boost = boost165; };
+  ceph = callPackage ../tools/filesystems/ceph {
+    boost = boost166.override { enablePython = true; };
+  };
   ceph-dev = ceph;
 
   certmgr = callPackage ../tools/security/certmgr { };