Install virtualenv only if missing

Author: danielhers

experiments/acl2017.sh

@@ -11,7 +11,7 @@ set -e
 # }
 mkdir -p hershcovich2017a
 cd hershcovich2017a
-pip install --user virtualenv
+python -m virtualenv --version || pip install --user virtualenv || true
 python -m virtualenv --python=/usr/bin/python3 venv
 . venv/bin/activate              # on bash
 pip install "tupa>=1.0,<1.1"

experiments/acl2018.sh

@@ -11,7 +11,7 @@ set -e
 # }
 mkdir -p hershcovich2018multitask
 cd hershcovich2018multitask
-pip install --user virtualenv
+python -m virtualenv --version || pip install --user virtualenv || true
 python -m virtualenv --python=/usr/bin/python3 venv
 . venv/bin/activate              # on bash
 pip install "tupa==1.3.2"