[devtools] Remove explicit version check, now that shebangs are python2.

build/dev.sh

@@ -18,23 +18,6 @@ source test/common.sh  # R_PATH
 
 export PYTHONPATH='.:vendor/'
 
-# In some distros, 'python' is python3, which confuses first-time developers.
-# https://github.com/oilshell/oil/issues/97
-readonly PYTHON_VERSION="$(python2 --version 2>&1)"
-
-# bash weirdness: VERSION_REGEX must NOT be inline in the expression, and must
-# NOT be quoted.
-readonly VERSION_REGEX='Python (2\.7\.[0-9]+)'
-
-if [[ "${PYTHON_VERSION}" =~ $VERSION_REGEX ]]; then
-  true
-else
-  echo >&2 'FATAL: Oil dev requires Python 2.7.*'
-  echo >&2 "But you have '${PYTHON_VERSION}'"
-  echo >&2 'Hint: Use virtualenv to create a Python 2.7 environment.'
-  exit 1
-fi
-
 ubuntu-deps() {
   # python-dev: for pylibc
   # gawk: used by spec-runner.sh for the special match() function.