[gimp] build: remove unreleased <release> when building flatpak nightly.

[Jehan <jehanp src gnome org>]

commit 48b5f50a58b0e126fa9db4f960e25c6b918adde8
Author: Jehan <jehan girinstud io>
Date:   Thu Apr 4 12:25:41 2019 +0200

    build: remove unreleased <release> when building flatpak nightly.
    
    This breaks the flatpak tests at the end when we prepared a future
    <release> appdata tag. For released version, we must not do this, but
    for nightlies, it doesn't matter.

 build/flatpak/org.gimp.GIMP-nightly.json         |  6 ++++++
 build/flatpak/remove-future-appdata-release.xslt | 13 +++++++++++++
 2 files changed, 19 insertions(+)
---
diff --git a/build/flatpak/org.gimp.GIMP-nightly.json b/build/flatpak/org.gimp.GIMP-nightly.json
index c790ef1b74..760526777e 100644
--- a/build/flatpak/org.gimp.GIMP-nightly.json
+++ b/build/flatpak/org.gimp.GIMP-nightly.json
@@ -416,6 +416,12 @@
                     "type": "git",
                     "url": "https://gitlab.gnome.org/GNOME/gimp.git";,
                     "branch": "master"
+                },
+                {
+                    "type": "shell",
+                    "commands": [
+                        "xsltproc -o desktop/org.gimp.GIMP.appdata.xml.in.in 
build/flatpak/remove-future-appdata-release.xslt desktop/org.gimp.GIMP.appdata.xml.in.in"
+                    ]
                 }
             ],
            "post-install": [
diff --git a/build/flatpak/remove-future-appdata-release.xslt 
b/build/flatpak/remove-future-appdata-release.xslt
new file mode 100644
index 0000000000..c3bbcb13fe
--- /dev/null
+++ b/build/flatpak/remove-future-appdata-release.xslt
@@ -0,0 +1,13 @@
+<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform";>
+
+  <xsl:output  method="xml" omit-xml-declaration="no" encoding="UTF-8"/>
+
+  <xsl:template match="node()|@*">
+    <xsl:copy>
+       <xsl:apply-templates select="node()|@*"/>
+    </xsl:copy>
+  </xsl:template>
+
+  <xsl:template match="//release[@date='TODO']"/>
+
+</xsl:stylesheet>