[gimp/wip/Jehan/incremental-win-installer-improvements] build: job win-installer-nightly should return failure appropriately.

[Jehan <jehanp src gnome org>]

commit f010ce31a98d1e0c6efcf1407727633f9e3a349e
Author: Jehan <jehan girinstud io>
Date:   Tue May 18 21:13:11 2021 +0200

    build: job win-installer-nightly should return failure appropriately.

 build/windows/gitlab-ci/installer-gimp-msys2.sh | 7 +++++++
 1 file changed, 7 insertions(+)
---
diff --git a/build/windows/gitlab-ci/installer-gimp-msys2.sh b/build/windows/gitlab-ci/installer-gimp-msys2.sh
index 29089b1c42..cce0c6fd09 100644
--- a/build/windows/gitlab-ci/installer-gimp-msys2.sh
+++ b/build/windows/gitlab-ci/installer-gimp-msys2.sh
@@ -33,3 +33,10 @@ MINOR_VERSION=`grep 'm4_define(\[gimp_minor_version' configure.ac |sed 's/m4_def
 MICRO_VERSION=`grep 'm4_define(\[gimp_micro_version' configure.ac |sed 
's/m4_define(\[gimp_micro_version.*\[\([0-9]*\)\].*/\1/'`
 cd build/windows/installer
 ./compile.bat ${MAJOR_VERSION}.${MINOR_VERSION}.${MICRO_VERSION} ../../.. gimp-w32 gimp-w64 ../../.. 
gimp-w32 gimp-w64
+
+# Test if the installer was created and return success/failure.
+if [ -f "_Output/gimp-${MAJOR_VERSION}.${MINOR_VERSION}.${MICRO_VERSION}-setup.exe" ]; then
+  exit 0
+else
+  exit 1
+fi