Improve possible to run Pieman from any directory

bootstrap/50-firstboot.sh

@@ -34,7 +34,7 @@ if is_alpine; then
     echo "rm -f /etc/local.d/90-firstboot.start" >> "${ETC}"/local.d/90-firstboot.start
 elif is_debian_based; then
     install_exec "${FIRSTBOOT}" "${ETC}"/rc.firstboot
-    install_exec files/etc/rc.local "${ETC}"/rc.local
+    install_exec "${PIEMAN_DIR}"/files/etc/rc.local "${ETC}"/rc.local
 
     # /etc/rc.firstboot has to destroy itself and its traces after first run.
     cat <<EOT >> "${ETC}"/rc.firstboot

essentials.sh

@@ -65,10 +65,10 @@ IMAGE_MENDER_ARTIFACT=3
 # Returns:
 #     None
 activate_venv_if_exists() {
-    if [[ -d venv ]] && [[ -f venv/bin/python ]]; then
+    if [[ -d "${PIEMAN_DIR}"/venv ]] && [[ -f "${PIEMAN_DIR}"/venv/bin/python ]]; then
         info "activating the venv virtual environment"
         # shellcheck disable=SC1091
-        source ./venv/bin/activate
+        source "${PIEMAN_DIR}"/venv/bin/activate
     fi
 }
 

helpers/others.sh

@@ -81,7 +81,7 @@ add_option_to_pm_options() {
 # Returns:
 #     None
 create_keyring() {
-    for key in keys/"${PIECES[0]}"/*; do
+    for key in "${PIEMAN_DIR}"/keys/"${PIECES[0]}"/*; do
         gpg --no-default-keyring --keyring="${KEYRING}" --import "${key}"
     done
 }
@@ -96,7 +96,7 @@ create_keyring() {
 # Returns:
 #     None
 mark_keys_as_trusted() {
-    for key in keys/"${PIECES[0]}"/*; do
+    for key in "${PIEMAN_DIR}"/keys/"${PIECES[0]}"/*; do
         local key_name=""
 
         key_name=$(basename "${key}")