Git help please - checking out old commit doesn't find lib/gnulib.mk.in.

[Alan Mackenzie]

Hello, Emacs.

I'm attempting to check out a moderately old version of Emacs with:

    $ git checkout 10c0e1c

.  This appears to work.  I then attempt to build it with:

    $ time make -j17 bootstrap

.  This fails with:

    make: *** No rule to make target 'lib/gnulib.mk.in', needed by 'Makefile'.  
Stop.

.  It would appear that the git checkout has failed to restore the state
of the given commit, in that it hasn't restored the indicated file.  Is
this in fact the case?

What do I have to do to restore this version in a state I can build.
(System: 64-bit GNU (Gentoo)).

-- 
Alan Mackenzie (Nuremberg, Germany).