PYTHON IndexError: tuple index out of range

Question

Would really appreciate feedback on this issue

import subprocess

def main():
'''
Here's where the whole thing starts.
'''
#Edit this constant to change the file name in the git log command.
FILE_NAME = 'file1.xml'

#Do the git describe command to get the tag names.
gitDescribe = 'git describe --tags `git rev-list --tags --max-count=2`'
print ('Invoking: {0}'.format(gitDescribe))
p1 = subprocess.Popen(gitDescribe, shell=True, stdout=subprocess.PIPE)
output = p1.stdout.read()

#Get the first 2 tags from the output.
parsedOutput = output.split('\n')
tag1 = parsedOutput[0]
tag2 = parsedOutput[1]

print('First revision: {0}'.format(tag1))
print('Second revision: {1}'.format(tag2))
#Do the git log command for the revision comparison.
gitLog = 'git log {0}..{1} --pretty=format:"%an %h %ad %d %s" --date=short --topo-order --no-merges {2}'.format(tag1, tag2, FILE_NAME)
print('Invoking: {0}'.format(gitLog))
p2 = subprocess.Popen(gitLog, shell=True, stdout=subprocess.PIPE)
output = p2.stdout.read()
print(output)

if __name__ == "__main__":
    main()

...

bash-3.2$ python pygit5.py 
Invoking: git describe --tags `git rev-list --tags --max-count=2`

First revision: 14.5.5.1
Traceback (most recent call last):
File "pygit5.py", line 31, in <module>
main()
File "pygit5.py", line 22, in main
print('Second revision: {1}'.format(tag2))
IndexError: tuple index out of range

Answer 1

tag2 is only a single value, like tag1, so you can't reference item[1]. No doubt you mean

print('Second revision: {0}'.format(tag2))

Answer 2

When using formatting as you have, remember that in most programming languages, counting starts from zero. So since tag2 only carries one value, the following line:

print('Second revision: {1}'.format(tag2))

Should really be:

print('Second revision: {0}'.format(tag2))

You can also leave it empty for simple scripts if using python 2.7+:

print('Second revision: {}'.format(tag2))

Or provide them in any order with named variables:

print('Second revision: {revisiontag}'.format(revisiontag=tag2))