fetch-pack: avoid repeatedly re-scanning pack directory

diff --git a/builtin/rev-parse.c b/builtin/rev-parse.c
index 32788a9f86427237d0f4838362c1e3bc722fa258..25e225f06717bfc2fd1f988269ff503a907d9302 100644 (file)
--- a/builtin/rev-parse.c
+++ b/builtin/rev-parse.c
@@ -230,6 +230,7 @@ static int try_difference(const char *arg)
        const char *next;
        const char *this;
        int symmetric;
+       static const char head_by_default[] = "HEAD";
 
        if (!(dotdot = strstr(arg, "..")))
                return 0;
@@ -241,9 +242,20 @@ static int try_difference(const char *arg)
        next += symmetric;
 
        if (!*next)
-               next = "HEAD";
+               next = head_by_default;
        if (dotdot == arg)
-               this = "HEAD";
+               this = head_by_default;
+
+       if (this == head_by_default && next == head_by_default &&
+           !symmetric) {
+               /*
+                * Just ".."?  That is not a range but the
+                * pathspec for the parent directory.
+                */
+               *dotdot = '.';
+               return 0;
+       }
+
        if (!get_sha1_committish(this, sha1) && !get_sha1_committish(next, end)) {
                show_rev(NORMAL, end, next);
                show_rev(symmetric ? NORMAL : REVERSED, sha1, this);