source: install/setversion.py @ 4201

import subprocess

def MakeByte2str(arg):
    '''Convert output from subprocess pipes (bytes) to str (unicode) in Python 3.
    In Python 2: Leaves output alone (already str). 
    Leaves stuff of other types alone (including unicode in Py2)
    Works recursively for string-like stuff in nested loops and tuples.

    typical use::
        out = MakeByte2str(out)
    or::
        out,err = MakeByte2str(s.communicate())
    
    '''
    if isinstance(arg,str): return arg
    if isinstance(arg,bytes): return arg.decode()
    if isinstance(arg,list):
        return [MakeByte2str(i) for i in arg]
    if isinstance(arg,tuple):
        return tuple([MakeByte2str(i) for i in arg])
    return arg
svn = 'svn' # assume in path
cmd = [svn,'info','https://subversion.xray.aps.anl.gov/pyGSAS/trunk']
s = subprocess.Popen(cmd,
                    stdout=subprocess.PIPE,stderr=subprocess.PIPE)
out,err = MakeByte2str(s.communicate())
if err:
    print ('subversion error!\nout=%s'%out)
    print ('err=%s'%err)
    sys.exit(1)
for line in out.split('\n'):
    if line.startswith('Rev'):
        version = line.split()[1].strip()
        break
else:
    print ('Version not found!\nout=%s'%out)
    sys.exit(1)
for fil in 'g2complete/meta.yaml','g2full/construct.yaml':
    fp = open(fil+'.template','r')
    out = fp.read().replace('**Version**',version)
    fp.close()
    print('Creating',fil)
    fp = open(fil,'w')
    fp.write(out)
    fp.close()