compile+doc/3: deal with older gits

  - detect/warn git version < 1.6.2
  - create documentation with details on client-side workaround
  - change the "git init --bare" to (older) "git --bare init", since the old
    syntax still works anyway

doc/3-faq-tips-etc.mkd

@@ -3,6 +3,7 @@
 In this document:
 
   * common errors and mistakes
+  * git version dependency
   * other errors, warnings, notes...
   * differences from gitosis
       * two levels of access rights checking
@@ -25,6 +26,35 @@ In this document:
     the client side also :-)  In fact gitolite prepends `$REPO_BASE` when it
     is required anyway, so you shouldn't do the same thing!
 
+### git version dependency
+
+Here's a workaround for a version dependency that the normal flow of gitolite
+has.
+
+When you edit your config file to create a new repo, and run
+`src/gl-compile-conf`, gitolite creates an empty, bare repo for you.
+Normally, you're expected to clone this on the client side, and start working
+-- make your first commit(s), then push, etc.
+
+However, cloning an empty repo requires a server side git version that is at
+least 1.6.2.  Gitolite detects this when creating a repo, and warns you.
+
+The workaround is to use the older (gitosis-style) method on the client:
+create an empty repo locally, make a commit or two, set an "origin" remote,
+and then push.  Something like:
+
+    mkdir my-new-project
+    cd    my-new-project
+    git init
+    git commit --allow-empty -m 'Initial repository'
+    # or, if your client side git is too old for --allow-empty, just make some
+    # files, "git add" them, then "git commit"
+    git remote add origin git@gitolite-server:my-new-project.git
+    git push origin master:master
+
+Once this is done, the repo is available for cloning by anyone else in the
+normal way, since it's not empty anymore.
+
 ### other errors, warnings, notes...
 
   * cloning an empty repo is only possible with clients greater than 1.6.2.

src/gl-compile-conf

@@ -192,6 +192,13 @@ close $compiled_fh or die "$ATTN close compiled-conf failed: $!\n";
 # did not have that luxury, so it was forced to detect the first push and
 # create it then
 
+# but it turns out not everyone has "modern" gits :)
+my $git_version = `git --version`;
+my ($gv_maj, $gv_min, $gv_patchrel) = ($git_version =~ m/git version (\d+)\.(\d+)\.(\d+)/);
+die "$ATTN I can't understand $git_version\n" unless ($gv_maj >= 1);
+$git_version = $gv_maj*10000 + $gv_min*100 + $gv_patchrel;  # now it's "normalised"
+my $git_too_old = 0;
+
 # repo-base needs to be an absolute path for this loop to work right
 # so if it was not already absolute, prefix $HOME.
 my $repo_base_abs = ( $REPO_BASE =~ m(^/) ? $REPO_BASE : "$ENV{HOME}/$REPO_BASE" );
@@ -202,12 +209,18 @@ for my $repo (keys %repos)
     {
         mkdir("$repo.git") or die "$ATTN mkdir $repo.git failed: $!\n";
         wrap_chdir("$repo.git");
-        system("git init --bare");
+        system("git --bare init");
         system("cp $GL_ADMINDIR/src/update-hook.pl hooks/update");
         chmod 0755, "hooks/update";
         wrap_chdir("$repo_base_abs");
+        $git_too_old++ if $git_version < 10602;     # that's 1.6.2 to you
     }
 }
+warn "\n\t\t***** WARNING *****\n" .
+    "\tyour git version is older than 1.6.2\n" .
+    "\tgitolite will work but you MUST read the section on\n" .
+    "\t\"git version dependency\" in doc/3-faq-tips-etc.mkd\n"
+    if $git_too_old;
 
 # ----------------------------------------------------------------------------
 #       "compile" ssh authorized_keys