git-config bugfix + backward compat breakage in usage of 'config'

(1) the backward compat breakage: you can't create empty-valued config
    keys anymore.  That is, you can't do the eqvt of the following shell
    command using gitolite

        git config foo.bar ""

(2) fixed a bug where this:

        repo foo
            config foo.bar =

    when queried using

        gitolite git-config -r foo .

    would return even the empty valued ones, which -- remember! -- are
    not supposed to exist anymore.

    Fixing this bug allows situations like this to not show the admin
    repo in gitweb:

        repo [a-z].*
            config gitweb.owner = P-h B

        repo gitolite-admin
            config gitweb.owner =

----

background...

Somewhere in g3 (well actually in 057506b), we lost the ability to
distinguish
    config foo.bar  =   ""
from
    config foo.bar =

I decided that conflating them is more intuitive for most people,
because a survey [1] revealed that no one seemed to want the equivalent
of the following shell command:

----

[1] ...of a (small prime greater than 1) number of people on #git

doc/git-config.mkd

@@ -23,9 +23,9 @@ For example:
         config foo.bar = ""
         config foo.baz =
 
-This does either a plain "git config section.key value" (for the first 3
+This does either a plain "git config section.key value" (for the first 2
-examples above) or "git config --unset-all section.key" (for the last
+examples above) or "git config --unset-all section.key" (for the last 2
-example).  Other forms of the `git config` command (`--add`, the
+examples).  Other forms of the `git config` command (`--add`, the
 `value_regex`, etc) are not supported.
 
 >   ----

src/lib/Gitolite/Conf/Load.pm

@@ -114,7 +114,7 @@ sub access {
 }
 
 sub git_config {
-    my ( $repo, $key ) = @_;
+    my ( $repo, $key, $empty_values_OK ) = @_;
     $key ||= '.';
 
     return {} if repo_missing($repo);
@@ -149,6 +149,15 @@ sub git_config {
     # and the final map does this:
     #                 'foo.bar'=>'repo'  ,      'foodbar'=>'repoD'
 
+    # now some of these will have an empty key; we need to delete them unless
+    # we're told empty values are OK
+    unless ($empty_values_OK) {
+        my($k, $v);
+        while (($k, $v) = each %ret) {
+            delete $ret{$k} if not $v;
+        }
+    }
+
     trace( 3, map { ( "$_" => "-> $ret{$_}" ) } ( sort keys %ret ) );
     return \%ret;
 }

src/triggers/post-compile/update-git-configs

@@ -37,7 +37,7 @@ for my $pr (@$lpr) {
 sub fixup_config {
     my $pr = shift;
 
-    my $gc = git_config( $pr, '.' );
+    my $gc = git_config( $pr, '.', 1 );
     while ( my ( $key, $value ) = each( %{$gc} ) ) {
         next if $key =~ /^gitolite-options\./;
         if ( $value ne "" ) {