`make sdist` target fails horribly if `lndir` is unavailable

In the top level Makefile the comment above the sdist target says:

# Just running `./boot && ./configure && make sdist` should work, so skip
# phase 0 and 1 and don't build any dependency files.

but when I try that (both for master and the ghc-8.0 branch, I get:

cd sdistprep/ghc/ghc-8.1.20160320 && for i in mk rules docs distrib bindisttest
    libffi includes utils docs rts compiler ghc driver libraries libffi-tarballs
    iserv; do mkdir -p $i; ( cd $i && lndir /home/erikd/Git/ghc-upstream/$i ); done
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
/bin/bash: lndir: command not found
ghc.mk:1205: recipe for target 'sdist-ghc-prep-tree' failed
make[1]: *** [sdist-ghc-prep-tree] Error 127

Trac metadata

Trac field	Value
Version	7.10.3
Type	Bug
TypeOfFailure	OtherFailure
Priority	normal
Resolution	Unresolved
Component	Build System
Test case
Differential revisions
BlockedBy
Related
Blocking
CC
Operating system
Architecture