Ramya,
I just removed the keystone directory and pulled it again. Make sure you have all the build requisite packages installed.
I have, since working with the Buildroot process a little while, discovered a few ways of 'un-breaking' a build that will not
complete. In the above instance, the log suggests that the problem happened during the build of 'host-ccache'.
For the exact point of error, you can go into build-generic/build.log and have a look. But in this case, lets assume host-ccache is
the problem. You can just remove the directory under build-generic/buildroot.build/build/host-ccache-3.7.12,
or whatever the current package name is. Then restart the make, and Buildroot will go fetch a clean copy of that
package and try to rebuild it. It seems to me that it is not too hard to get Buildroot into a phase that it is not happy.
Paul