Update git module to handle branches better

This drops the branch option.  The version option is overloaded
to mean either a sha1, branch, or tag.  This also adds the option
'remote' which defaults to 'origin'.
clone() was simplified by removing the checkout operation.  That
happens later when switch_version() is called.

Added the methods get_branches(), is_remote_branch(), and
is_local_branch().  get_branches() returns an array listing all
of the branches for the git repository.  is_remote_branch() checks
whether the arguments supplied correspond to a remote branch.
Similarly, is_local_branch() checks for a local branch.

The pull() method now checks to see if it is on the desired branch.
If not, it checks out the requested branch and then does a pull.
This should keep issue #604 still fixed.

switch_version(), formerly switchver(), looks to see if it is
checking out a branch.  If a branch, it checks it out with the --track
option.  This type of checkout was in pull() before.

Updated pull, clone, and switch_version to return (rc, out, err).

git

@@ -71,8 +71,8 @@ for x in items:
 
 dest = params['dest']
 repo = params['repo']
-branch  = params.get('branch', 'master')
 version = params.get('version', 'HEAD')
+remote = params.get('remote', 'origin')
 
 # ===========================================
 
@@ -84,7 +84,7 @@ def get_version(dest):
    sha = sha[0].split()[1]
    return sha
 
-def clone(repo, dest, branch):
+def clone(repo, dest):
    ''' makes a new git repo if it does not already exist '''
    try:
        os.makedirs(os.path.dirname(dest))
@@ -94,14 +94,7 @@ def clone(repo, dest, branch):
    cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    (out, err) = cmd.communicate()
    rc = cmd.returncode
-   
-   if branch is None or rc != 0: 
-     return (out, err)
-
-   os.chdir(dest)
-   cmd = "git checkout -b %s origin/%s" % (branch, branch) 
-   cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-   return cmd.communicate()
+   return (rc, out, err)
 
 def reset(dest):
    '''
@@ -121,52 +114,67 @@ def switchLocalBranch( branch ):
    cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
    return cmd.communicate()
 
-def pull(repo, dest, branch):
-   ''' updates repo from remote sources '''
+def get_branches(dest):
     os.chdir(dest)
+    branches = []
     cmd = "git branch -a"
     cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-   (gbranch_out, gbranch_err) = cmd.communicate()
-
-   try:
-      m = re.search( '^\* (\S+|\(no branch\))$', gbranch_out, flags=re.M )
-      cur_branch = m.group(1)
-      m = re.search( '\s+remotes/origin/HEAD -> origin/(\S+)', gbranch_out, flags=re.M )
-      default_branch = m.group(1)
-   except:
-      fail_json(msg="could not determine branch data - received: %s" % gbranch_out)
-
-   if branch is None:
-      if cur_branch != default_branch:
-         (out, err) = switchLocalBranch( default_branch )
-
-      cmd = "git pull -u origin"
-
-   elif branch == cur_branch:
-      cmd = "git pull -u origin"
-
+    out, err = cmd.communicate()
+    if cmd.returncode != 0:
+        fail_json(msg="Could not determine branch data - received %s" % out)
+    for line in out.split('\n'):
+        branches.append(line.strip())
+    return branches
+
+def is_remote_branch(dest, remote, branch):
+    branches = get_branches(dest)
+    rbranch = 'remotes/%s/%s' % (remote, branch)
+    if rbranch in branches:
+        return True
     else:
-      m = re.search( '^\s+%s$' % branch, gbranch_out, flags=re.M ) #see if we've already checked it out
-      if m is None:
-         cmd = "git checkout --track -b %s origin/%s" % (branch, branch)
+        return False
 
+def is_local_branch(dest, branch):
+    branches = get_branches(dest)
+    lbranch = '%s' % branch
+    if lbranch in branches:
+        return True
     else:
-         cmd = "git pull -u origin"
+        return False
 
+def pull(repo, dest, version):
+    ''' updates repo from remote sources '''
+    os.chdir(dest)
+    branches = get_branches(dest)
+    cur_branch = ''
+    for b in branches:
+        if b.startswith('* '):
+            cur_branch = b
+    if is_local_branch(dest, version) and version != cur_branch:
+        (out, err) = switchLocalBranch(version)
+
+    cmd = "git pull -u origin"
     cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
-   return cmd.communicate()
+    out, err = cmd.communicate()
+    rc = cmd.returncode
+    return (rc, out, err)
 
-def switchver(version, dest):
+def switch_version(dest, remote, version):
     ''' once pulled, switch to a particular SHA or tag '''
     os.chdir(dest)
+    cmd = ''
     if version != 'HEAD':
-      cmd = "git checkout %s --force" % version
+        if not is_local_branch(dest, version) and is_remote_branch(dest, remote, version):
+            cmd = "git checkout --track -b %s %s/%s" % (version, remote, version)
+        else:
+            cmd = "git checkout --force %s" % version
     else:
         # is there a better way to do this?
         cmd = "git rebase origin"
     cmd = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.PIPE)
     (out, err) = cmd.communicate()
-   return (out, err)
+    rc = cmd.returncode
+    return (rc, out, err)
  
 
 gitconfig = os.path.join(dest, '.git', 'config')
@@ -178,14 +186,16 @@ out, err, status = (None, None, None)
 
 before = None
 if not os.path.exists(gitconfig):
-   (out, err) = clone(repo, dest, branch)
+   (rc, out, err) = clone(repo, dest)
+   if rc != 0:
+      fail_json(out=out, err=err, rc=rc)
 else:
    # else do a pull   
    before = get_version(dest)
    (rc, out, err) = reset(dest)
    if rc != 0:
-      fail_json(out=out, err=err)
-   (out, err) = pull(repo, dest, branch)
+      fail_json(out=out, err=err, rc=rc)
+   (rc, out, err) = pull(repo, dest, version)
 
 # handle errors from clone or pull
 
@@ -195,7 +205,7 @@ if out.find('error') != -1 or err.find('ERROR') != -1:
 # switch to version specified regardless of whether
 # we cloned or pulled
 
-(out, err) = switchver(version, dest)
+(rc, out, err) = switch_version(dest, remote, version)
 if err.find('error') != -1:
    fail_json(out=out, err=err)