build.py: handle the case of no satisfiable packages

diff --git a/build.py b/build.py
index 37a585a..ca04796 100755 (executable)
--- a/build.py
+++ b/build.py
@@ -7,6 +7,7 @@ import lzma
 import os.path
 import sqlite3
 import subprocess
+import time
 
 from common import decompress_stream, yield_lines, yield_chunks
 
@@ -39,7 +40,12 @@ def main():
     db = sqlite3.connect("db", detect_types=sqlite3.PARSE_DECLTYPES)
     with contextlib.closing(db.cursor()) as cur:
         cur.execute("SELECT source, version, depstate.architecture FROM depstate JOIN depcheck ON depstate.architecture = depcheck.architecture WHERE satisfiable = 1 AND giveback = 0 ORDER BY random() LIMIT 1;")
-        source, version, architecture = cur.fetchone()
+        row = cur.fetchone()
+    if not row:
+        print("no package satisfiable")
+        time.sleep(60)
+        return
+    source, version, architecture = row
     print("building %s_%s for %s" % (source, version, architecture))
     timestamp, success, filename, giveback = do_build(source, version, architecture)
     with contextlib.closing(db.cursor()) as cur: