version.h:25:37: error: 'c283e79' undeclared (first use in this function)

[garlick]

I just hit this problem in one of my PR's that @grondo hit in #2014. All the ubuntu, but not centos, travis builders failed with

  CC       libflux_la-version.lo
In file included from version.c:15:0:
version.c: In function 'flux_core_version':
version.h:25:37: error: 'c283e79' undeclared (first use in this function)
 #define FLUX_CORE_VERSION_MAJOR     c283e79
                                     ^
version.c:25:18: note: in expansion of macro 'FLUX_CORE_VERSION_MAJOR'
         *major = FLUX_CORE_VERSION_MAJOR;
                  ^~~~~~~~~~~~~~~~~~~~~~~
version.h:25:37: note: each undeclared identifier is reported only once for each function it appears in
 #define FLUX_CORE_VERSION_MAJOR     c283e79
                                     ^
version.c:25:18: note: in expansion of macro 'FLUX_CORE_VERSION_MAJOR'
         *major = FLUX_CORE_VERSION_MAJOR;
                  ^~~~~~~~~~~~~~~~~~~~~~~
version.c:29:41: error: expected expression before ';' token
         *patch = FLUX_CORE_VERSION_PATCH;
                                         ^
In file included from version.c:15:0:
version.h:33:63: error: expected expression before '<<' token
                                      (FLUX_CORE_VERSION_PATCH << 0))
                                                               ^
version.c:30:12: note: in expansion of macro 'FLUX_CORE_VERSION_HEX'
     return FLUX_CORE_VERSION_HEX;
            ^~~~~~~~~~~~~~~~~~~~~
version.c:31:1: error: control reaches end of non-void function [-Werror=return-type]
 }
 ^

Configure output this:

checking Major version... c283e79
checking Minor version... 9
checking Point version... 

[grondo]

We are now hitting this in Travis on flux-core@master:

https://travis-ci.org/flux-framework/flux-core/jobs/495643517

Looks like the git fetch --unshallow is failing due to this error:

git fetch --unshallow --tags
fatal: unknown value for config 'protocol.version': 2

This fetch --unshallow should probably be moved outside of docker, to ensure we're using a git compatible with the default .config -- at least on Travis-CI.