lorry: Only log number of commits pruned from marks files

Logging each pruned commit can result in very long logs for some
repositories.  This is a problem for Lorry Controller because job
status updates result in copying the entire log and not just the new
log lines.

There's not much value in listing all the commit hashes, so log the
number of commits instead.  Update the test case accordingly.

1 files changed, 6 insertions, 2 deletions

diff --git a/lorry b/lorry
index c2019d4..9a10045 100755
--- a/lorry
+++ b/lorry
@@ -743,6 +743,7 @@ class Lorry(cliapp.Application):
         mark_re = re.compile(r':(\S+) ([0-9a-f]{40,})\n')
         marks_temp_fd, marks_temp_name = \
             tempfile.mkstemp(dir=os.path.dirname(marks_name))
+        n_pruned = 0
         try:
             with open(marks_temp_fd, 'w') as marks_out, \
                  open(marks_name, 'r') as marks_in:
@@ -759,11 +760,14 @@ class Lorry(cliapp.Application):
                     elif match.group(2) in reachable:
                         marks_out.write(line)
                     else:
-                        self.progress('%s: pruning unreachable commit %s'
-                                      % (marks_name, match.group(2)))
+                        n_pruned += 1
 
             # On success, replace marks file with temporary file
             os.rename(marks_temp_name, marks_name)
+
+            if n_pruned:
+                self.progress('%s: pruned %d unreachable commit(s)'
+                              % (marks_name, n_pruned))
         except:
             # On failure, delete temporary file
             os.unlink(marks_temp_name)