/usr/bin/gitmkdirs is in gnuit 4.9.5-3+b2.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
| 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 | #! /bin/sh
# mkinstalldirs --- make directory hierarchy
# Author: Noah Friedman <friedman@prep.ai.mit.edu>
# Created: 1993-05-16
# Last modified: 1994-03-25
# Public domain
# Note: this is not supposed to be used as a stand alone program.
errstatus=0
for file in ${1+"$@"} ; do 
    set fnord `echo ":$file" | sed -ne 's/^:\//#/;s/^://;s/\// /g;s/^#/\//;p'`
    shift
    pathcomp=
    for d in ${1+"$@"} ; do
	pathcomp="$pathcomp$d"
	case "$pathcomp" in
	    -* ) pathcomp=./$pathcomp ;;
	esac
	if test ! -d "$pathcomp"; then
	    mkdir "$pathcomp" || errstatus=$?
	fi
	pathcomp="$pathcomp/"
    done
done
exit $errstatus
# mkinstalldirs ends here
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