contrib: Support github pull request gitian-build

Author: ken2812221

contrib/gitian-build.py

@@ -135,6 +135,7 @@ def main():
 
     parser = argparse.ArgumentParser(usage='%(prog)s [options] signer version')
     parser.add_argument('-c', '--commit', action='store_true', dest='commit', help='Indicate that the version argument is for a commit or branch')
+    parser.add_argument('-p', '--pull', action='store_true', dest='pull', help='Indicate that the version argument is the number of a github repository pull request')
     parser.add_argument('-u', '--url', dest='url', default='https://github.com/bitcoin/bitcoin', help='Specify the URL of the repository. Default is %(default)s')
     parser.add_argument('-v', '--verify', action='store_true', dest='verify', help='Verify the Gitian build')
     parser.add_argument('-b', '--build', action='store_true', dest='build', help='Do a Gitian build')
@@ -196,13 +197,21 @@ def main():
         exit(1)
 
     # Add leading 'v' for tags
+    if args.commit and args.pull:
+        raise Exception('Cannot have both commit and pull')
     args.commit = ('' if args.commit else 'v') + args.version
-    print(args.commit)
 
     if args.setup:
         setup()
 
     os.chdir('bitcoin')
+    if args.pull:
+        subprocess.check_call(['git', 'fetch', args.url, 'refs/pull/'+args.version+'/merge'])
+        os.chdir('../gitian-builder/inputs/bitcoin')
+        subprocess.check_call(['git', 'fetch', args.url, 'refs/pull/'+args.version+'/merge'])
+        args.commit = subprocess.check_output(['git', 'show', '-s', '--format=%H', 'FETCH_HEAD'], universal_newlines=True).strip()
+        args.version = 'pull-' + args.version
+    print(args.commit)
     subprocess.check_call(['git', 'fetch'])
     subprocess.check_call(['git', 'checkout', args.commit])
     os.chdir(workdir)