[BUG?] t9500 --debug prints "sh: ++GIT_BINDIR++/git: not found"

Hi,

Trying to run t9500-gitweb-standalone-no-errors.sh, I find:

 $ sh t9500-gitweb-standalone-no-errors.sh --debug
 ok 1 - no commits: projects_list (implicit)
 sh: ++GIT_BINDIR++/git: not found
 ok 2 - no commits: projects_index
 sh: ++GIT_BINDIR++/git: not found
 ok 3 - no commits: .git summary (implicit)
 [...]

config.mak reads:

 CFLAGS = -g -O2 -Wall -Wdeclaration-after-statement
 NO_OPENSSL=1
 NO_EXPAT=1
 COMPUTE_HEADER_DEPENDENCIES=1
 USE_NSEC=1
 ASCIIDOC8=1
 ASCIIDOC_NO_ROFF=1

and there is no config.mak.autogen or other source of build flags.

Ideas?  Is this expected behavior?