Fix a test fail when no bwrap was available

Fixes fontconfig/fontconfig#201
3 jobs for issue/201 in 18 minutes and 9 seconds (queued for 38 seconds)
Status Job ID Name Coverage
  Build
passed #1074776
mingw-build

00:16:57

passed #1074774
shared-build

00:05:08

passed #1074775
static-build

00:05:23