Boostrap tar cannot exec xz

[Carlos Sánchez de La Lama]

Hi Ludo,

still trying too bootstrap linux-powerpc. I find the boostrap binary
"tar" fails to execute xz (which is un turn required to build make on
continue the bootstrap process), because it can not find bash.

The problem was introduced in your commit

74d637397b44a90d2dbc2ac100b38591dd4f81eb

which upgraded tar to 1.29. That commit also added the substitution of
"/bin/sh" to "<bash-store-path>/bin/sh" in src/system.c when compiling
tar, which is fine in general, but gets broken when %static-binaries
does a remove-store-reference for all the static binaries.

Is that substitution really needed?

BR

Carlos