segfault if remote repository cannot be fetched
apk segfaults if fetching a remote repository has failed (e.g. due to HTTP 404 error).
Program received signal SIGSEGV, Segmentation fault.
apk_istream_error (is=is@entry=0xfffffffe, err=err@entry=-2) at ../src/apk_io.h:95
(gdb) bt
#0 apk_istream_error (is=is@entry=0xfffffffe, err=err@entry=-2)
at ../src/apk_io.h:95
#1 0xb6f5abcc in apk_istream_close_error (r=-2, is=0xfffffffe)
at ../src/apk_io.h:125
#2 apk_istream_tee (from=0xfffffffe, to=0xb6fef620, flags=0,
cb=<optimized out>, cb_ctx=0x0) at ../src/io.c:468
#3 0xb6f53ae8 in apk_cache_download (db=db@entry=0x31740 <db>,
repo=repo@entry=0x31824 <db+228>, pkg=0x0, autoupdate=-1090528832,
autoupdate@entry=1, cb=0x0, cb_ctx=0x0) at ../src/database.c:669
#4 0xb6f54b6c in apk_repository_update (repo=0x31824 <db+228>,
db=0x31740 <db>) at ../src/database.c:2133
#5 apk_db_add_repository (_db=..., _repository=...) at ../src/database.c:2258
#6 0xb6f4cd0c in apk_blob_for_each_segment (blob=..., split=0xbefffbb8 "",
cb=0xb6f54838 <apk_db_add_repository>, ctx=ctx@entry=0x31740 <db>)
at ../src/blob.c:305
#7 0xb6f50780 in add_repos_from_file (ctx=ctx@entry=0x31740 <db>, dirfd=3,
file=0xb6f6b1c3 <error reading variable>) at ../src/database.c:1400
#8 0xb6f561bc in apk_db_open (db=db@entry=0x31740 <db>,
ac=ac@entry=0x31db0 <ctx>) at ../src/database.c:1668
#9 0x00014414 in main (argc=0, argv=0xbefffe6c) at ../src/apk.c:474