Fix getChunks when reading gzip files.

Since gzip files are always finished, we don't need to freeze the state
of the logfile by determining where the end of the file is.

buildbot/status/builder.py

@@ -334,9 +334,13 @@ def getChunks(self, channels=[], onlyText=False):
         # yield() calls.
 
         f = self.getFile()
-        offset = 0
-        f.seek(0, 2)
-        remaining = f.tell()
+        if not self.finished:
+            offset = 0
+            f.seek(0, 2)
+            remaining = f.tell()
+        else:
+            offset = 0
+            remaining = None
 
         leftover = None
         if self.runEntries and (not channels or
@@ -354,8 +358,12 @@ def _generateChunks(self, f, offset, remaining, leftover,
         chunks = []
         p = LogFileScanner(chunks.append, channels)
         f.seek(offset)
-        data = f.read(min(remaining, self.BUFFERSIZE))
-        remaining -= len(data)
+        if remaining is not None:
+            data = f.read(min(remaining, self.BUFFERSIZE))
+            remaining -= len(data)
+        else:
+            data = f.read(self.BUFFERSIZE)
+
         offset = f.tell()
         while data:
             p.dataReceived(data)
@@ -366,8 +374,11 @@ def _generateChunks(self, f, offset, remaining, leftover,
                 else:
                     yield (channel, text)
             f.seek(offset)
-            data = f.read(min(remaining, self.BUFFERSIZE))
-            remaining -= len(data)
+            if remaining is not None:
+                data = f.read(min(remaining, self.BUFFERSIZE))
+                remaining -= len(data)
+            else:
+                data = f.read(self.BUFFERSIZE)
             offset = f.tell()
         del f