Try to use /usr/bin/test or /bin/test to work around missing features.
The builtin "test" of Solaris 8 /bin/sh doesn't understand -nt.
#!/bin/sh
mkdir t
cd t
hg init
echo This is file a1 > a
echo This is file b1 > b
hg add a b
hg commit -m "commit #0" -d "1000000 0"
echo This is file b22 > b
hg commit -m"comment #1" -d "1000000 0"
hg update 0
rm b
hg commit -A -m"comment #2" -d "1000000 0"
# in theory, we shouldn't need the "-y" below, but it prevents
# this test from hanging when "hg update" erroneously prompts the
# user for "keep or delete"
hg update -y 1
exit 0