Backwards compatibility for python 2.4

Python 2.4 doesn't allow try...except...finally clauses, see PEP
341. Also, yield statements inside try...finally is not allowed. The
commit changes the logic to no longer use those syntactical features.

Signed-off-by: Nicolas Sebrecht <ni.s@laposte.net>

offlineimap/accounts.py

@@ -84,8 +84,10 @@ class SigListener(Queue):
                         self.folderlock.release()
                         yield (folder, quick)
                         self.folderlock.acquire()
-        finally:
+        except:
             self.folderlock.release()
+            raise
+        self.folderlock.release()
 
 def getaccountlist(customconfig):
     return customconfig.getsectionlist('Account')
@@ -183,10 +185,11 @@ class AccountSynchronizationMixin:
         #might need changes here to ensure that one account sync does not crash others...
         if not self.refreshperiod:
             try:
-                self.sync(siglistener)
-            except:
-                self.ui.warn("Error occured attempting to sync account " + self.name \
-                    + ": " + str(sys.exc_info()[1]))
+                try:
+                    self.sync(siglistener)
+                except:
+                    self.ui.warn("Error occured attempting to sync account " + self.name \
+                                 + ": " + str(sys.exc_info()[1]))
             finally:
                 self.ui.acctdone(self.name)
 
@@ -196,10 +199,11 @@ class AccountSynchronizationMixin:
         looping = 1
         while looping:
             try:
-                self.sync(siglistener)
-            except:
-                self.ui.warn("Error occured attempting to sync account " + self.name \
-                    + ": " + str(sys.exc_info()[1]))
+                try:
+                    self.sync(siglistener)
+                except:
+                    self.ui.warn("Error occured attempting to sync account " + self.name \
+                                 + ": " + str(sys.exc_info()[1]))
             finally:
                 looping = self.sleeper(siglistener) != 2
                 self.ui.acctdone(self.name)