bootstrap_system.sh checks if ~/Impala is an existing directory, and if it isn't then clones Impala to that path. Once this is done this script jumps to ~/Impala and starts a build.
In case someone clones the Impala sources to a custom directory, sources the Impala configs there and then invokes bootstrap_development.sh or bootstrap_system.sh then in the background the build is actually performed in ~/Impala instead of the custom dir. Taking into account that Impala is not sourced from ~/Impala, but the build is done there, this can result some strange build failures.
My proposal is to move the following code behind a command line parameter that is off by default: