[commit: ghc] wip/fix-docs: fixup! circleci: Install sphinx and TexLive (8b6f933)

[git at git.haskell.org]

Repository : ssh://git@git.haskell.org/ghc

On branch  : wip/fix-docs
Link       : http://ghc.haskell.org/trac/ghc/changeset/8b6f93317f4219fcc9bdb815b9da85821432c237/ghc

>---------------------------------------------------------------

commit 8b6f93317f4219fcc9bdb815b9da85821432c237
Author: Ben Gamari <ben at smart-cactus.org>
Date:   Sun Aug 5 19:25:48 2018 -0400

    fixup! circleci: Install sphinx and TexLive


>---------------------------------------------------------------

8b6f93317f4219fcc9bdb815b9da85821432c237
 .circleci/prepare-system.sh | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.circleci/prepare-system.sh b/.circleci/prepare-system.sh
index 08769f2..462d445 100755
--- a/.circleci/prepare-system.sh
+++ b/.circleci/prepare-system.sh
@@ -9,8 +9,8 @@ fail() {
 
 hackage_index_state="@1522046735"
 
-if [[ -z "$BUILD_SPHINX_HTML" ]]; then BUILD_SPHINX_HTML=YES; fi
-if [[ -z "$BUILD_SPHINX_PDF" ]]; then BUILD_SPHINX_PDF=YES; fi
+if [[ -z "${BUILD_SPHINX_HTML:-}" ]]; then BUILD_SPHINX_HTML=YES; fi
+if [[ -z "${BUILD_SPHINX_PDF:-}" ]]; then BUILD_SPHINX_PDF=YES; fi
 
 cat > mk/build.mk <<EOF
 V=1