The bootstrap script currently generates a THANKS file by grepping through the git shortlog and running an extended regular expression command on the resulting stream using sed (line 48):
git shortlog -se 6c976bd..HEAD \
|grep -v @apache.org \|
| sed -E "s/^[[:blank:]]
[[:digit:]]+[[:blank:]]/ * /" >> THANKS
BSD sed uses the '-E' option to interpret regular expressions as extended (modern) regular expressions rather than basic regular expressions (BRE's). GNU sed uses the '-r' option for this behavior.
The bootstrap script should be modified to detect the proper flag to use. I am currently using a patch which checks the system's uname to determine the flag.