[gnome-photos/wip/rishi/no-git-release-builds] build: Avoid requiring Git for release tarballs

[Debarshi Ray <debarshir src gnome org>]

commit e9e5cb3ad19865b319fb7a86670b06f7fbe1c32d
Author: Debarshi Ray <debarshir gnome org>
Date:   Sat Oct 13 14:23:21 2018 +0200

    build: Avoid requiring Git for release tarballs
    
    It's a tad nicer to not require Git when building release tarballs.
    While Git is definitely widely available, it's just one more that would
    have to be installed in the buildroots. Therefore, use of Git is
    avoided for 'plain' builds.

 meson.build | 14 ++++++++++----
 1 file changed, 10 insertions(+), 4 deletions(-)
---
diff --git a/meson.build b/meson.build
index 3f6e1552..a0fdc369 100644
--- a/meson.build
+++ b/meson.build
@@ -30,10 +30,17 @@ po_dir = join_paths(source_root, 'po')
 
 top_inc = include_directories('.')
 
-git = find_program('git')
+photos_commit_id = ''
 if not photos_buildtype.contains('plain')
+  git = find_program('git')
+
   run_command(git, '-C', source_root, 'submodule', 'sync', '--recursive')
   run_command(git, '-C', source_root, 'submodule', 'update', '--init', '--recursive')
+
+  res = run_command(git, '-C', source_root, 'describe')
+  if res.returncode() == 0
+    photos_commit_id = res.stdout().strip()
+  endif
 endif
 
 cc = meson.get_compiler('c')
@@ -44,9 +51,8 @@ config_h.set_quoted('PACKAGE_TARNAME', meson.project_name())
 config_h.set_quoted('PACKAGE_URL', 'https://wiki.gnome.org/Apps/Photos')
 config_h.set_quoted('PACKAGE_VERSION', meson.project_version())
 
-res = run_command(git, '-C', source_root, 'describe')
-if res.returncode() == 0
-  config_h.set_quoted('PACKAGE_COMMIT_ID', res.stdout().strip())
+if photos_commit_id != ''
+  config_h.set_quoted('PACKAGE_COMMIT_ID', photos_commit_id)
 endif
 
 config_h.set_quoted('G_LOG_DOMAIN', meson.project_name())