Fix `rbenv install --list` for definitions auto-discovery

The build definitions auto-discovered from rbenv plugins would
previously not appear in `--list` results due to discovery process
taking place too late.

bin/rbenv-install

@@ -51,6 +51,15 @@ indent() {
   sed 's/^/  /'
 }
 
+# Add `share/ruby-build/` directory from each rbenv plugin to the list of
+# paths where build definitions are looked up.
+shopt -s nullglob
+for plugin_path in "$RBENV_ROOT"/plugins/*/share/ruby-build; do
+  RUBY_BUILD_DEFINITIONS="${RUBY_BUILD_DEFINITIONS}:${plugin_path}"
+done
+export RUBY_BUILD_DEFINITIONS
+shopt -u nullglob
+
 unset FORCE
 unset SKIP_EXISTING
 unset KEEP
@@ -162,15 +171,6 @@ if [ -z "${RUBY_BUILD_CACHE_PATH}" ] && [ -d "${RBENV_ROOT}/cache" ]; then
   export RUBY_BUILD_CACHE_PATH="${RBENV_ROOT}/cache"
 fi
 
-# Add `share/ruby-build/` directory from each rbenv plugin to the list of
-# paths where build definitions are looked up.
-shopt -s nullglob
-for plugin_path in "$RBENV_ROOT"/plugins/*/share/ruby-build; do
-  RUBY_BUILD_DEFINITIONS="${RUBY_BUILD_DEFINITIONS}:${plugin_path}"
-done
-export RUBY_BUILD_DEFINITIONS
-shopt -u nullglob
-
 # Default RBENV_VERSION to the globally-specified Ruby version. (The
 # REE installer requires an existing Ruby installation to run. An
 # unsatisfied local .ruby-version file can cause the installer to

test/rbenv.bats

@@ -95,3 +95,18 @@ ${RBENV_ROOT}/plugins/bar/share/ruby-build
 ${RBENV_ROOT}/plugins/foo/share/ruby-build
 OUT
 }
+
+@test "list build definitions from plugins" {
+  mkdir -p "${RBENV_ROOT}/plugins/foo/share/ruby-build"
+  mkdir -p "${RBENV_ROOT}/plugins/bar/share/ruby-build"
+  stub_ruby_build "--definitions : echo \$RUBY_BUILD_DEFINITIONS | tr ':' $'\\n'"
+
+  run rbenv-install --list
+  assert_success
+  assert_output <<OUT
+Available versions:
+  
+  ${RBENV_ROOT}/plugins/bar/share/ruby-build
+  ${RBENV_ROOT}/plugins/foo/share/ruby-build
+OUT
+}