When docs are explicitly requested, require Sphinx>=1.6.0. When docs are
explicitly disabled, don't bother to check for Sphinx at all. If docs
are set to "auto", attempt to locate Sphinx, but continue onward if it
wasn't located.

For the case that --enable-pypi is set to 'enabled' (the default) but
docs are set to 'auto' (also the default), do not actually consult PyPI
to install Sphinx. Only perform this action when docs are requested
explicitly.

Signed-off-by: John Snow <jsnow@redhat.com>
---
 configure | 27 +++++++++++++++++++++++++--
 1 file changed, 25 insertions(+), 2 deletions(-)

diff --git a/configure b/configure
index 0881fffc14..a247b9491c 100755
--- a/configure
+++ b/configure
@@ -1122,14 +1122,14 @@ fi
 
 # Suppress writing compiled files
 python="$python -B"
-
+mkvenv="$python ${source_path}/python/scripts/mkvenv.py"
 
 mkvenv_flags=""
 if test "$pypi" = "enabled" ; then
     mkvenv_flags="--online"
 fi
 
-if ! $python "${source_path}/python/scripts/mkvenv.py" ensure \
+if ! $mkvenv ensure \
      $mkvenv_flags \
      --dir "${source_path}/python/wheels" \
      --diagnose "meson" \
@@ -1144,6 +1144,29 @@ fi
 # *exclusively*.
 meson="$(cd pyvenv/bin; pwd)/meson"
 
+# Conditionally ensure Sphinx is installed.
+
+mkvenv_flags=""
+if test "$pypi" = "enabled" -a "$docs" = "enabled" ; then
+    mkvenv_flags="--online"
+fi
+
+if test "$docs" != "disabled" ; then
+    if ! $mkvenv ensure \
+         $mkvenv_flags \
+         --diagnose "sphinx-build" \
+         "sphinx>=1.6.0" ;
+    then
+        if test "$docs" = "enabled" ; then
+            exit 1
+        fi
+        echo "Sphinx not found/usable, disabling docs."
+        docs=disabled
+    else
+        docs=enabled
+    fi
+fi
+
 echo "MKVENV ok!"
 
 # Probe for ninja
-- 
2.39.2