Allow building deb package for older systems.

debian/changelog

+latex-theme-tpt (0.9.1-2) UNRELEASED; urgency=medium
+
+  * Make dependency on tex-common more explicit, override version.
+
+ -- Cedric Ware <cedric.ware@telecom-paristech.fr>  Fri, 31 Jul 2020 15:50:00 +0200
+
 latex-theme-tpt (0.9.1-1) UNRELEASED; urgency=medium
 
   * Initial debian packaging.

debian/control

@@ -2,7 +2,7 @@ Source: latex-theme-tpt
 Section: tex
 Priority: optional
 Maintainer: Cedric Ware <cedric.ware@telecom-paristech.fr>
-Build-Depends: debhelper (>= 9.0.0), texlive-pictures (>= 2016), texlive-latex-recommended (>= 2016), texlive-latex-extra (>= 2016), fig2dev, latex-make, latexmk
+Build-Depends: debhelper (>= 9.0.0), tex-common, texlive-pictures (>= 2016), texlive-latex-recommended (>= 2016), texlive-latex-extra (>= 2016), fig2dev, latex-make, latexmk
 Standards-Version: 3.9.3
 
 Package: latex-theme-tpt

debian/rules

@@ -5,3 +5,10 @@
 override_dh_auto_install:
 	$(MAKE) -f $$(pwd)/debian/packaging.mk prefix=$$(pwd)/debian/latex-theme-tpt/usr install-tex
 	$(MAKE) -f $$(pwd)/debian/packaging.mk prefix=$$(pwd)/debian/latex-theme-tpt-doc-fr/usr install-doc
+
+# dh_installtex adds a dependency to the currently-installed tex-common
+# version, but we may want to install the package onto older systems.
+override_dh_installtex:
+	dh_installtex
+	perl -pi.orig -E 's{(tex-common\s+)\((.*?)\)}{$${1}(>= 6.06)}g' \
+		debian/*.substvars