[jhbuild] Fix 'jhbuild sysdeps' when ninja is not installed

[Michael Catanzaro <mcatanzaro src gnome org>]

commit 159367256a1cffa6f9daad0d10fa90f5bbff67ec
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Mon Dec 5 15:11:49 2016 -0600

    Fix 'jhbuild sysdeps' when ninja is not installed
    
    This regressed in 73b433d89cd4c2496e9d44659a486d4ea0e2a20c, which is sad
    because it means nobody has bothered to report that our Build GNOME
    guide has been broken for the past two months.
    
    We cannot check for ninja binary in __init__ because it gets called from
    sysdeps, so we end up failing because the thing we're trying to install
    is not already installed. Check before each point of use instead.

 jhbuild/modtypes/meson.py |    6 ++++--
 1 files changed, 4 insertions(+), 2 deletions(-)
---
diff --git a/jhbuild/modtypes/meson.py b/jhbuild/modtypes/meson.py
index a42c6c8..d694a3b 100644
--- a/jhbuild/modtypes/meson.py
+++ b/jhbuild/modtypes/meson.py
@@ -52,9 +52,8 @@ class MesonModule(MakeModule, DownloadableModule):
         self.skip_install_phase = skip_install_phase
         self.force_non_srcdir_builds = True
         self.supports_install_destdir = True
-        self.find_ninja()
 
-    def find_ninja(self):
+    def ensure_ninja_binary(self):
         for f in ['ninja', 'ninja-build']:
             if inpath(f, os.environ['PATH'].split(os.pathsep)):
                 self.ninja_binary = f
@@ -131,6 +130,7 @@ class MesonModule(MakeModule, DownloadableModule):
     def do_clean(self, buildscript):
         buildscript.set_action(_('Cleaning'), self)
         builddir = self.get_builddir(buildscript)
+        self.ensure_ninja_binary()
         buildscript.execute(self.ninja_binary + ' clean', cwd=builddir, extra_env=self.extra_env)
     do_clean.depends = [PHASE_CONFIGURE]
     do_clean.error_phases = [PHASE_FORCE_CHECKOUT, PHASE_CONFIGURE]
@@ -138,6 +138,7 @@ class MesonModule(MakeModule, DownloadableModule):
     def do_build(self, buildscript):
         buildscript.set_action(_('Building'), self)
         builddir = self.get_builddir(buildscript)
+        self.ensure_ninja_binary()
         buildscript.execute(self.ninja_binary, cwd=builddir, extra_env=self.extra_env)
     do_build.depends = [PHASE_CONFIGURE]
     do_build.error_phases = [PHASE_FORCE_CHECKOUT, PHASE_CONFIGURE]
@@ -151,6 +152,7 @@ class MesonModule(MakeModule, DownloadableModule):
         destdir = self.prepare_installroot(buildscript)
         extra_env = (self.extra_env or {}).copy()
         extra_env['DESTDIR'] = destdir
+        self.ensure_ninja_binary()
         buildscript.execute(self.ninja_binary + ' install', cwd=builddir, extra_env=extra_env)
         self.process_install(buildscript, self.get_revision())
     do_install.depends = [PHASE_BUILD]