PDI with zsh: environment variables are not set correctly

sourcing /path/pdi/install/share/pdi/env.bash does not set correctly the PDI_DIR variable, therefore all commands relying on it misbehaves.

in zsh:

$ unset PDI_DIR
$ source /path/pdi/install/share/pdi/env.bash
$ echo $PDI_DIR
PDI_DIR : /path

in bash (expected behaviour) :

$ unset PDI_DIR
$ source /path/pdi/install/share/pdi/env.bash
$ echo $PDI_DIR
PDI_DIR : /path/pdi/install