Improve error message for non-fast-forward push. Closes: #720896.

[dgit.git] / dgit

diff --git a/dgit b/dgit
index a8077a809887596a97172c94a032685ca7a80c90..71b042302dfa1e88eed02571bc47381e748f12a1 100755 (executable)
--- a/dgit
+++ b/dgit
@@ -639,8 +639,14 @@ sub rev_parse ($) {
 
 sub is_fast_fwd ($$) {
     my ($ancestor,$child) = @_;
-    my $mb = cmdoutput @git, qw(merge-base), $ancestor, $child;
-    return rev_parse($mb) eq rev_parse($ancestor);
+    my @cmd = (@git, qw(merge-base), $ancestor, $child);
+    my $mb = cmdoutput_errok @cmd;
+    if (defined $mb) {
+       return rev_parse($mb) eq rev_parse($ancestor);
+    } else {
+       $?==256 or failedcmd @cmd;
+       return 0;
+    }
 }
 
 sub git_fetch_us () {
@@ -978,7 +984,10 @@ sub cmd_push {
        git_fetch_us();
     }
     if (fetch_from_archive()) {
-       is_fast_fwd(lrref(), 'HEAD') or die;
+       is_fast_fwd(lrref(), 'HEAD') or
+           fail "dgit push: HEAD is not a descendant".
+               " of the archive's version.\n".
+               "$us: To overwrite it, use git-merge -s ours ".lrref().".";
     } else {
        $new_package or
            fail "package appears to be new in this suite;".