image: Expand PV to avoid AUTOREV parsing failures

image: Expand PV to avoid AUTOREV parsing failures

Currently, setting PV to include SRCPV for build-appliance results in:

bb.data_smart.ExpansionError: Failure expanding variable SRCPV, expression was
${@bb.fetch2.get_srcrev(d)} which triggered exception FetchError: Fetcher
failure: Fetch command export ftp_proxy="http://proxy.yocto.io:5187/"; export
FTP_PROXY="http://proxy.yocto.io:5187/"; export PATH="${TMPDIR}/work/
qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot-native/usr/bin/python3-native:${TMPDIR}/work/
qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot-native/usr/bin/python3-native:${TMPDIR}/work/
qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot-native/usr/bin/python3-native:/home/pokybuild/
yocto-autobuilder/yocto-worker/buildtools/build/scripts:${TMPDIR}/
work/qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot-native/usr/bin/x86_64-poky-linux:${TMPDIR}/work/
qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot/usr/bin/crossscripts:${TMPDIR}/work/qemux86_64-poky-linux/
build-appliance-image/fetcheravoidrecurse-r0/recipe-sysroot-native/usr/sbin:
${TMPDIR}/work/qemux86_64-poky-linux/build-appliance-image/
fetcheravoidrecurse-r0/recipe-sysroot-native/usr/bin:${TMPDIR}/work/
qemux86_64-poky-linux/build-appliance-image/fetcheravoidrecurse-r0/
recipe-sysroot-native/sbin:${TMPDIR}/work/qemux86_64-poky-linux/
build-appliance-image/fetcheravoidrecurse-r0/recipe-sysroot-native/bin:/home/
pokybuild/yocto-autobuilder/yocto-worker/buildtools/build/bitbake/bin:${TMPDIR}
/hosttools"; export HOME="/home/pokybuild"; git -c core.fsyncobjectfiles=0
ls-remote git://git.yoctoproject.org/poky  failed with exit code 127, output:
/bin/sh: 1: git: not found

This is because PV is being expanded when TMPDIR is unset.

Expand PV in advance to avoid this problem.

Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>