repo.remote().fetch("--dry-run") can produce assertion failure

[josefsachsconning]

>>> import git
>>> repo = git.Repo("C:/Users/s2sajs/Documents/GitHub/Reactive.jl")
>>> fr = repo.remote().fetch("--dry-run")
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "C:\Python27\lib\site-packages\git\remote.py", line 657, in fetch
    res = self._get_fetch_info_from_stderr(proc, progress or RemoteProgress())
  File "C:\Python27\lib\site-packages\git\remote.py", line 576, in _get_fetch_info_from_stderr
    assert l_fil >= l_fhi, "len(%s) <= len(%s)" % (l_fil, l_fhi)
AssertionError: len(5) <= len(6)

[Byron]

Which version of GitPython are you using ?
What is the remote that you are trying to pull ?

In case you are not using the latest version from pypi, please try again with that one.
Thanks

[josefsachsconning]

I'm using GitPython-2.0.3. That's the latest, right?

C:\Users\s2sajs\Documents\GitHub\Reactive.jl>git config --get remote.origin.url
https://github.com/JuliaLang/Reactive.jl.git

C:\Users\s2sajs\Documents\GitHub\Reactive.jl>git status
On branch master
Your branch is up-to-date with 'origin/master'.

nothing to commit, working directory clean

C:\Users\s2sajs\Documents\GitHub\Reactive.jl>git fetch --dry-run
From https://github.com/JuliaLang/Reactive.jl
   4d4417f..0c032a3  master     -> origin/master

[Byron]

I was unable to reproduce it. Here is what I tried:

import git
r = git.Repo.clone_from('https://github.com/JuliaLang/Reactive.jl', 'here')
r.remote().fetch()
r.remote().fetch('--dry-run')

Does this work for you ? Maybe there is more to it, like the git version installed on the system.

$ git --version
git version 2.7.4 (Apple Git-66)

[josefsachsconning]

C:\Users\s2sajs\Documents\GitHub\Reactive.jl>git --version
git version 1.9.5.msysgit.0

The behavior is dependent on the condition of the working copy. If I try the fetch in a freshly cloned working copy, it works just fine.

[Byron]

This is what I get when running the command git-python runs from the terminal:

$ git fetch -v origin
From https://github.com/JuliaLang/Reactive.jl
 = [up to date]      master     -> origin/master
 = [up to date]      cjh/cleanup -> origin/cjh/cleanup
 = [up to date]      gh-pages   -> origin/gh-pages
 = [up to date]      next       -> origin/next
 = [up to date]      teh/imageview_warmups -> origin/teh/imageview_warmups

Could you run that on your end ?

[josefsachsconning]

C:\Users\s2sajs\Documents\GitHub\Reactive.jl>git fetch -v origin
From https://github.com/JuliaLang/Reactive.jl
   4d4417f..0c032a3  master     -> origin/master
 = [up to date]      cjh/cleanup -> origin/cjh/cleanup
 = [up to date]      gh-pages   -> origin/gh-pages
 = [up to date]      next       -> origin/next
 = [up to date]      teh/imageview_warmups -> origin/teh/imageview_warmups

[Byron]

I still can't reproduce it - even when manipulating my local repository to update the remote master:

➜  here git:(master) git fetch -v origin --dry-run
From https://github.com/JuliaLang/Reactive.jl
   7a3e5e9..0c032a3  master     -> origin/master
 = [up to date]      cjh/cleanup -> origin/cjh/cleanup
 = [up to date]      gh-pages   -> origin/gh-pages
 = [up to date]      next       -> origin/next
 = [up to date]      teh/imageview_warmups -> origin/teh/imageview_warmups

Maybe it's related to the git version somehow, or to windows. In any case, what you could do is to have a look at the line that throws the assertion, and add some debug-printing yourself. That way you can find out which line it fails to handle correctly. I am not sure what else I can do here, unfortunately.

Personally I'd think it does not matter whether or not you use --dry-run either, as the output should be exactly the same.

[josefsachsconning]

Thanks for trying. In case it helps anyone, fetch_info_lines is

[u'   4d4417f..0c032a3  master     -> origin/master\n',
 u' = [up to date]      cjh/cleanup -> origin/cjh/cleanup\n',
 u' = [up to date]      gh-pages   -> origin/gh-pages\n',
 u' = [up to date]      next       -> origin/next\n',
 u' = [up to date]      teh/imageview_warmups -> origin/teh/imageview_warmups\n']

and fetch_head_info is

[u"4d4417fd437dd5e11c5c00c0c38e2920f42d1ab5\t\tbranch 'master' of https://github.com/JuliaLang/Reactive.jl\n",
 u"dd4b19f52781ab9b6369b850e5c497b0709daefe\tnot-for-merge\tbranch 'cjh/cleanup' of https://github.com/JuliaLang/Reactive.jl\n",
 u"7fbea37f4fcc20eaf34402de89d7a247be9368cb\tnot-for-merge\tbranch 'gh-pages' of https://github.com/JuliaLang/Reactive.jl\n",
 u"9c5d5d1dc7d30e8eed6deedc9f44493573e5c968\tnot-for-merge\tbranch 'next' of https://github.com/JuliaLang/Reactive.jl\n",
 u"6241b420ac9ae36f7bac4142b9f241970eea2539\tnot-for-merge\tbranch 'teh/imageview_warmups' of https://github.com/JuliaLang/Reactive.jl\n",
 u"d7a2bd36ead56cf1e0bdad6b04af9e6a1803860b\tnot-for-merge\tbranch 'teh/throttle_typ' of https://github.com/JuliaLang/Reactive.jl\n"]

That demonstrates that l_fil < l_fhi.
The problem, apparently, is that teh/throttle_typ is in fetch_head_info but not in fetch_info_lines.

[Byron]

Indeed ! This assertion was the cause for many issues in the past, and so far there was no good fix for it. This is the comment at the respective line: # NOTE: We assume to fetch at least enough progress lines to allow matching each fetch head line with it.

The problem is that I never understood why git would sometimes do that, or what the correct behaviour is. Should GitPython provide only partial information, or should it simply ignore the partial data ?

Currently it matches the lines one on one, maybe it's safe to just ignore extra lines in the fetch head info ... and get rid of this issue once and for all.

[josefsachsconning]

Yes, my inclination would be to ignore extra lines in the fetch head info.

[josefsachsconning]

Did you get that backwards? Don't you want to ignore extra lines in fetch_head_info, not extra lines in fetch_info_lines?

[Byron]

Thanks for the review ! I totally did - fix is on the way.