[PATCH] commit: clarify "could not read 'template'" message

Fabrício noticed that when the "[commit] template" configuration is
misconfigured to point to a nonexistent file, ever since v1.7.4.2
(see 2140b140, 2011-02-25), "git commit" fails in a seemingly
mysterious way:

	$ git commit
	fatal: could not read 'template': No such file or directory

In olden times, the message instead said

	Commit template file does not exist.

which makes it a little clearer that the --template option or
corresponding configuration item is being misused.  Let's move a
little in that direction, by saying "could not read commit message
template 'template'".

Note that the origin of the setting in the motivating ~/.gitignore is
still unknown.  Depending on the answer, it might be nice to start
ignoring nonexistent commit templates again; if the problem is
widespread, hopefully there will be more reports soon.

Noticed-by: Fabrício Nascimento [off-list ref]
Analysis-by: Michael Witten [off-list ref]
Signed-off-by: Jonathan Nieder <redacted>
---
Hi again,

Fabrício Nascimento wrote:

I have no idea what could have set the variable. Time Machine tells me the
only changes on the .gitconfig file happened on August 12th, the day I've
flagged the bug. I know I've made a brew upgrade on all my packages (that
included git) the night before, and then the bug appeared the day after. I
should have done only git stats, commit, pull and push.

Thanks for these details.  I looked through the packages in brew, but no
obvious clues.

At least the problem could have been easier to debug.  How about this
patch, to start?

 builtin/commit.c |    3 ++-
 1 files changed, 2 insertions(+), 1 deletions(-)

diff --git a/builtin/commit.c b/builtin/commit.c
index cb738574..d029ec03 100644
--- a/builtin/commit.c
+++ b/builtin/commit.c

@@ -703,7 +703,8 @@ static int prepare_to_commit(const char *index_file, const char *prefix,
 		hook_arg1 = "squash";
 	} else if (template_file) {
 		if (strbuf_read_file(&sb, template_file, 0) < 0)
-			die_errno(_("could not read '%s'"), template_file);
+			die_errno(_("could not read commit message template '%s'"),
+				  template_file);
 		hook_arg1 = "template";
 		clean_message_contents = 0;
 	}

-- 
1.7.6