Display version origin with non-installed versions

This is useful as an indicator where it is coming from.

libexec/rbenv-version-name

@@ -23,6 +23,6 @@ if version_exists "$RBENV_VERSION"; then
 elif version_exists "${RBENV_VERSION#ruby-}"; then
   echo "${RBENV_VERSION#ruby-}"
 else
-  echo "rbenv: version \`$RBENV_VERSION' is not installed" >&2
+  echo "rbenv: version \`$RBENV_VERSION' is not installed (set by $(rbenv-version-origin))" >&2
   exit 1
 fi

libexec/rbenv-which

@@ -52,7 +52,7 @@ done
 if [ -x "$RBENV_COMMAND_PATH" ]; then
   echo "$RBENV_COMMAND_PATH"
 elif ! [ -d "${RBENV_ROOT}/versions/${RBENV_VERSION}" ]; then
-  echo "rbenv: version \`$RBENV_VERSION' is not installed" >&2
+  echo "rbenv: version \`$RBENV_VERSION' is not installed (set by $(rbenv-version-origin))" >&2
   exit 1
 else
   echo "rbenv: $RBENV_COMMAND: command not found" >&2

test/exec.bats

@@ -17,7 +17,7 @@ create_executable() {
 @test "fails with invalid version" {
   export RBENV_VERSION="2.0"
   run rbenv-exec ruby -v
-  assert_failure "rbenv: version \`2.0' is not installed"
+  assert_failure "rbenv: version \`2.0' is not installed (set by RBENV_VERSION environment variable)"
 }
 
 @test "completes with names of executables" {

test/version-name.bats

@@ -49,7 +49,7 @@ setup() {
 
 @test "missing version" {
   RBENV_VERSION=1.2 run rbenv-version-name
-  assert_failure "rbenv: version \`1.2' is not installed"
+  assert_failure "rbenv: version \`1.2' is not installed (set by RBENV_VERSION environment variable)"
 }
 
 @test "version with prefix in name" {

test/which.bats

@@ -59,7 +59,7 @@ create_executable() {
 @test "version not installed" {
   create_executable "2.0" "rspec"
   RBENV_VERSION=1.9 run rbenv-which rspec
-  assert_failure "rbenv: version \`1.9' is not installed"
+  assert_failure "rbenv: version \`1.9' is not installed (set by RBENV_VERSION environment variable)"
 }
 
 @test "no executable found" {