Merge branch 'ls/p4-lfs'

Recent update to Git LFS broke "git p4" by changing the output from
its "lfs pointer" subcommand.

* ls/p4-lfs:
  git-p4: fix Git LFS pointer parsing
  travis-ci: express Linux/OS X dependency versions more clearly
  travis-ci: update Git-LFS and P4 to the latest version

git-p4.py

@@ -1064,8 +1064,15 @@ class GitLFS(LargeFileSystem):
         if pointerProcess.wait():
             os.remove(contentFile)
             die('git-lfs pointer command failed. Did you install the extension?')
-        pointerContents = [i+'\n' for i in pointerFile.split('\n')[2:][:-1]]
-        oid = pointerContents[1].split(' ')[1].split(':')[1][:-1]
+
+        # Git LFS removed the preamble in the output of the 'pointer' command
+        # starting from version 1.2.0. Check for the preamble here to support
+        # earlier versions.
+        # c.f. https://github.com/github/git-lfs/commit/da2935d9a739592bc775c98d8ef4df9c72ea3b43
+        if pointerFile.startswith('Git LFS pointer for'):
+            pointerFile = re.sub(r'Git LFS pointer for.*\n\n', '', pointerFile)
+
+        oid = re.search(r'^oid \w+:(\w+)', pointerFile, re.MULTILINE).group(1)
         localLargeFile = os.path.join(
             os.getcwd(),
             '.git', 'lfs', 'objects', oid[:2], oid[2:4],
@@ -1073,7 +1080,7 @@ class GitLFS(LargeFileSystem):
         )
         # LFS Spec states that pointer files should not have the executable bit set.
         gitMode = '100644'
-        return (gitMode, pointerContents, localLargeFile)
+        return (gitMode, pointerFile, localLargeFile)
 
     def pushFile(self, localLargeFile):
         uploadProcess = subprocess.Popen(