krb5 commit [krb5-1.17]: Fix spurious errors from kcmio_unix_socket_write

[Greg Hudson]

https://github.com/krb5/krb5/commit/d002daf4d7ad0db5d88a36b9dbbece12d7eaf9ff
commit d002daf4d7ad0db5d88a36b9dbbece12d7eaf9ff
Author: Robbie Harwood <rharwood at redhat.com>
Date:   Mon Nov 5 13:49:52 2018 -0500

    Fix spurious errors from kcmio_unix_socket_write
    
    Commit 33634a940166d0b21c3105bab8dcf5550fbbd678 accidentally changed
    the return value from kcmio_unix_socket_write to be the result of the
    write call.  Most commonly this resulted in it returning 8, which led
    to many commands failing with "Exec format error".
    
    (cherry picked from commit 3e76ea104cdaf22c4537833b203f8aeed1691f18)
    
    ticket: 8758
    version_fixed: 1.17

 src/lib/krb5/ccache/cc_kcm.c |    7 +++----
 1 files changed, 3 insertions(+), 4 deletions(-)

diff --git a/src/lib/krb5/ccache/cc_kcm.c b/src/lib/krb5/ccache/cc_kcm.c
index 2b9f82e..092ab7d 100644
--- a/src/lib/krb5/ccache/cc_kcm.c
+++ b/src/lib/krb5/ccache/cc_kcm.c
@@ -308,8 +308,9 @@ kcmio_unix_socket_write(krb5_context context, struct kcmio *io, void *request,
 
     for (;;) {
         ret = krb5int_net_writev(context, io->fd, sg, 2);
-        if (ret < 0)
-            ret = errno;
+        if (ret >= 0)
+            return 0;
+        ret = errno;
         if (ret != EPIPE || reconnected)
             return ret;
 
@@ -327,8 +328,6 @@ kcmio_unix_socket_write(krb5_context context, struct kcmio *io, void *request,
             return ret;
         reconnected = TRUE;
     }
-
-    return ret;
 }
 
 /* Read a KCM reply: 4-byte big-endian length, 4-byte big-endian status code,