Here's a version that's more likely to work.

svn path=/trunk/scripts/git-migration/; revision=1893

diff --git a/git-migrate b/git-migrate
index 458d903..f03884f 100755 (executable)
--- a/git-migrate
+++ b/git-migrate
@@ -5,6 +5,29 @@ import sys
 import subprocess
 import shutil
 
+def tagBase(pkg):
+    p = subprocess.Popen(['git', 'tag',
+                          '-l',
+                          'base'],
+                         cwd='%s.git' % pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    if p.stdout.read().strip() != '':
+        return
+    
+    p = subprocess.Popen(['git', 'rev-list',
+                          '--reverse',
+                          'master'],
+                         cwd='%s.git' % pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    base = p.stdout.read().split()[0]
+    
+    subprocess.check_call(['git', 'tag',
+                           'base',
+                           base],
+                          cwd='%s.git' % pkg)
+
 def clonePackage(base, pkg):
     if not os.path.isdir('%s.git' % pkg):
         if os.path.isdir(pkg):
@@ -34,16 +57,67 @@ def clonePackage(base, pkg):
     if len(p.stdout.read()) == 0:
         subprocess.check_call(['git', 'reset', '--soft', 'HEAD^'],
                               cwd='%s.git' % pkg)
+    
+    tagBase(pkg)
 
 def cloneAllPackages(base):
     for pkg in open('package-list'):
         clonePackage(base, pkg.strip())
 
 def mergeHistory(old_pkg, new_pkg, n):
+    n = int(n)
+    
     subprocess.check_call(['git', 'push',
                            '../%s.git' % new_pkg,
                            'master:refs/heads/%s' % old_pkg],
                           cwd='%s.git' % old_pkg)
+    
+    # Find the merge commit
+    if n == 0:
+        p = subprocess.Popen(['git', 'rev-parse',
+                              'base'],
+                             cwd='%s.git' % new_pkg,
+                             stdout=subprocess.PIPE)
+    else:
+        p = subprocess.Popen(['git', 'rev-list',
+                              '--reverse',
+                              '--boundary',
+                              '--skip=%s' % (n - 1),
+                              'base..master'],
+                             cwd='%s.git' % new_pkg,
+                             stdout=subprocess.PIPE)
+    p.wait()
+    new_rev = p.stdout.read().split()[0].strip('-')
+    
+    # Find any other parents of the merge commit
+    p = subprocess.Popen(['git', 'log',
+                          '-1',
+                          '--pretty=format:%P',
+                          new_rev],
+                         cwd='%s.git' % new_pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    parents = p.stdout.read().split()
+    
+    # Find the additional parent we're adding
+    p = subprocess.Popen(['git', 'rev-parse',
+                          old_pkg],
+                         cwd='%s.git' % new_pkg,
+                         stdout=subprocess.PIPE)
+    p.wait()
+    parents.append(p.stdout.read().strip())
+    
+    # Write out the grafts file
+    f = open('%s.git/info/grafts' % new_pkg, 'a')
+    print >>f, '%s %s' % (new_rev, ' '.join(parents))
+    f.close()
+    
+    # Run filter-branch
+    subprocess.call(['git', 'filter-branch',
+                     '--tag-name-filter', 'cat',
+                     '--',
+                     '--all'],
+                    cwd='%s.git' % new_pkg)
 
 def mergeHistories():
     merges = []