Bug 1283017

Description of problem:
dnf does not allow braces in variable substitution and makes it impossible to use with certain URLs in COPR ( see https://lists.fedoraproject.org/pipermail/devel/2015-October/215924.html ).

Version-Release number of selected component (if applicable):
Version used by COPR (not sure what it is).

How reproducible:
Always

Steps to Reproduce:
1. Use a variable with braces in a URL on COPR
2. Notice that variable is not expanded

Actual results:
Variable is not expanded with braces

Expected results:
Variable should be expanded with braces

Additional info:
Here's a Python script with several attempts at updating the regular expression ( see https://github.com/rpm-software-management/dnf/blob/bcbf36cbf140eb8a2a1e496e294b0c5102294446/dnf/conf/parser.py ) to support braces. My regex skills are pretty weak, so none of them are a the fully solution that I would hope for.

import re

_KEYCRE = re.compile(r"\${?(\w+)}?")
#_KEYCRE = re.compile(r"\$(\w+)|\${(\w+)}")
#_KEYCRE = re.compile(r'\$([{}]?)releasever\1')

def do_test(r, s):
    print s
    m = r.search(s)
    if m:
        print "Found", m.group(1), m.group()
    else:
        print "Negative"

do_test(_KEYCRE, 'this is a test of $releasever with spaces no braces')
do_test(_KEYCRE, 'this is a test of ${releasever} {with} spaces and braces')
do_test(_KEYCRE, 'this is a test of ${releasever}without spaces and braces')
do_test(_KEYCRE, 'this is a test of ${releasever with only left brace')
do_test(_KEYCRE, 'this is a test of $releasever} with only right brace')