[PATCH v2] help.c: fix autocorrect in work tree for bare repository

From: Simon Gerber <gesimu@gmail.com>

Currently, auto correction doesn't work reliably for commands which must run in a work tree (e.g. `git status`) in Git work trees which are created from a bare repository.

As far as I'm able to determine, this has been broken since commit 659fef199f (help: use early config when autocorrecting aliases, 2017-06-14), where the call to `git_config()` in `help_unknown_cmd()` was replaced with a call to `read_early_config()`. From what I can tell, the actual cause for the unexpected error is that we call `git_default_config()` in the `git_unknown_cmd_config` callback instead of simply returning `0` for config entries which we aren't interested in.

Calling `git_default_config()` in this callback to `read_early_config()` seems like a bad idea since those calls will initialize a bunch of state in `environment.c` (among other things `is_bare_repository_cfg`) before we've properly detected that we're running in a work tree.

All other callbacks provided to `read_early_config()` appear to only extract their configurations while simply returning `0` for all other config keys.

This commit changes the `git_unknown_cmd_config` callback to not call `git_default_config()`. Instead we also simply return `0` for config keys which we're not interested in.

Additionally the commit adds a new test case covering `help.autocorrect` in a work tree created from a bare clone.

Signed-off-by: Simon Gerber <gesimu@gmail.com>
---
    Fix autocorrect in work tree for bare repository
    
    Currently, auto correction doesn't work reliably for commands which must
    run in a work tree (e.g. git status) in Git work trees which are created
    from a bare repository.
    
    This patch adds a test case illustrating the issue and proposes a fix
    which adjusts the usage of read_early_config() in help_unknown_cmd() to
    match other usages of read_early_config(). In particular the patch
    removes the call to git_default_config() in the read config callback.
    
    Changes since v1 (both suggested by Junio):
    
     * Moved test to 9003
     * Squashed change and test into a single commit

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-git-1373%2Fsimu%2Ffix%2Fautocorrect-bare-worktree-v2
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-git-1373/simu/fix/autocorrect-bare-worktree-v2
Pull-Request: https://github.com/git/git/pull/1373

Range-diff vs v1:

 1:  d0a6eea93b5 < -:  ----------- tests: add test case for autocorrect in work tree for bare clone
 2:  7a2bef32439 ! 1:  4c598dbe778 help.c: don't call git_default_config in git_unknown_cmd_config
     @@ Metadata
      Author: Simon Gerber <gesimu@gmail.com>
      
       ## Commit message ##
     -    help.c: don't call git_default_config in git_unknown_cmd_config
     +    help.c: fix autocorrect in work tree for bare repository
      
          Currently, auto correction doesn't work reliably for commands which must
          run in a work tree (e.g. `git status`) in Git work trees which are
     @@ Commit message
          `git_default_config()`. Instead we also simply return `0` for config
          keys which we're not interested in.
      
     +    Additionally the commit adds a new test case covering `help.autocorrect`
     +    in a work tree created from a bare clone.
     +
          Signed-off-by: Simon Gerber <gesimu@gmail.com>
      
       ## help.c ##
     @@ help.c: static int git_unknown_cmd_config(const char *var, const char *value, vo
       }
       
       static int levenshtein_compare(const void *p1, const void *p2)
     +
     + ## t/t9003-help-autocorrect.sh ##
     +@@ t/t9003-help-autocorrect.sh: test_expect_success 'autocorrect can be declined altogether' '
     + 	test_line_count = 1 actual
     + '
     + 
     ++test_expect_success 'autocorrect works in work tree created from bare repo' '
     ++	git clone --bare . bare.git &&
     ++	git -C bare.git worktree add ../worktree &&
     ++	git -C worktree -c help.autocorrect=immediate stauts
     ++'
     ++
     + test_done

 help.c                      | 2 +-
 t/t9003-help-autocorrect.sh | 6 ++++++
 2 files changed, 7 insertions(+), 1 deletion(-)